t»«*4n 


5 


1 


REESE  LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

Class 


r\i . 


BARON  ALEXANDER  VON    HUMBOLDT 

From  the  painting  by  Professor  Julius  Schrader,  Esq.,  at  the  American  Museum  ot 
Natural  History,  owned  by  Morris  K.  Jesup 


THE   STORY    OF 

NINETEENTH-CENTURY 
SCIENCE 


BY 

HENRY  SMITH  WILLIAMS,  M.D. 


ILLUSTRATED 


HARPER  &  BROTHERS  PUBLISHERS 

NEW  YORK  AND  LONDON 

1901 


iULJ 


Copyright,  1900,  by  HENKY  SMITH  WILLIAMS. 

Ah  rights    reserved. 


CONTENTS 


CHAPTER  PAGE 

I.  SCIENCE  AT  THE  BEGINNING  OP  THE  CENTURY     ...  1 

II.  THE  CENTURY'S  PROGRESS  IN  ASTRONOMY 44 

III   THE  CENTURY'S  PROGRESS  IN  PALEONTOLOGY  ....  88 

IV.  THE  CENTURY'S  PROGRESS  IN  GEOLOGY •  .  123 

-V.  THE  CENTURY'S  PROGRESS  IN  METEOROLOGY    ....  157 
VI.  THE  CENTURY'S  PROGRESS  IN  PHYSICS.     THE  "IMPON- 
DERABLES"    192 

VII.  THE  ETHER  AND  PONDERABLE  MATTER 230 

VIII.  THE  CENTURY'S  PROGRESS  IN  CHEMISTRY 252 

IX.  THE  CENTURY'S  PROGRESS  IN  BIOLOGY.     THEORIES  OP 

ORGANIC  EVOLUTION 288 

X.  THE    CENTURY'S   PROGRESS   IN  ANATOMY   AND    PHYSI- 
OLOGY    321 

XI.  THE  CENTURY'S  PROGRESS  IN  SCIENTIFIC  MEDICINE     .  354 
XII.  THE  CENTURY'S  PROGRESS  IN  EXPERIMENTAL  PSYCHOL- 
OGY   395 

XIII.  SOME  UNSOLVED  SCIENTIFIC  PROBLEMS 433 

i.  SOLAR  AND  TELLURIC  PROBLEMS 435 

ii.  PHYSICAL  PROBLEMS 443 

m.  LIFE  PROBLEMS 449 

INDEX ,459 


ILLUSTRATIONS 


PAGE 

BARON   ALEXANDER  VON  HUMBOLDT Frontispiece 

HUMPHRY   DAVY 3 

JOSIAH   WEDGWOOD 6 

HERSCHEL   AND   HIS   SISTER   AT  THE   TELESCOPE 9 

JAMES  LOUIS  LAGRANGE 14 

JAMES  BUTTON  18 

— ' 

BENJAMIN   THOMPSON— COUNT   RUMFORD 25 

JOSKPH   PRIESTLY 30 

LAVOISIER   IN   HIS  LABORATORY 37 

EDWARD   JENNER 41 

FKIEDKICH   WILHELM   BESSEL 45 

HEINRICH   WILHELM  MATTHIAS  OLBERS 55 

SIR  JOHN   HERSCHEL 61 

THE    GREAT    REFRACTOR   OF    THE    NATIONAL    OBSERVATORY    AT 

WASHINGTON 67 

A   TYPICAL   STAR   CLUSTER — CENTAURI 71 

SPECTRA  OF  STARS  IN   CARINA 73 

STAR    SPECTRA 75 

LORD   ROSSE'S  TELESCOPE 77 

NO.   1— SIDEREAL   TIME,   15   HOURS,   50   MINUTES ) 

NO'.   2— SIDEREAL   TIME,    17   HOURS,  50  MINUTES ) 

THE   OXFORD  HELIOMETER 85 

GEORGES  CUVIER 92 

THE     WARREN     MASTODON,     FOUND     NEAR     NEWBURG,    ON     THE 

HUDSON 94 

V 


ILLUSTRATIONS 

PAGE 
THE    SKULL,    LACKING    THE   LOWER    JAW,    OF    EOBASILEUS    COR- 

NUTU8,  COPE 96 

METAMYNODON,    Oil    SWIMMING    RHINOCEROS,    FROM    SOUTH     DA- 
KOTA     .      . 101 

HYRACHYUS,    OR    RUNNING   RHINOCEROS,    FROM    SOUTHERN    WYO- 
MING       103 

PROFESSOR   E.    D.    COPE 106 

PROTOROHIPPUS,   THE   ANCESTRAL   FOUR-TOED    HORSE    .       .       .      .       110 

PROFESSOR  O.    C.    MARSH 0      .       112 

THE   EVOLUTION   OF   A    HORSE'S    FOOT   AND   OF   A    HORSE'S    HEAD      115 
FOOTPRINTS      OF      REPTILES      FOUND      IN      CONNECTICUT      SAND- 
STONE    .      . 118 

TITANOTHERE  FROM   SOUTH   DAKOTA   120 

THE  RESULTS   OF   EROSION   BY   RUNNING   WATER 127 

THE  RESULTS  OF   EROSION  BY   WIND 181 

A  MOUNTAIN  CARVED 'FROM   HORIZONTAL   STRATA 133 

LOUIS  JEAN   RODOLPH   AGASSIZ ) 

ADAM  SEDGWICK,    F.R.S.      .' f 

JAMES  DWIGHT   DANA ) 

SIR  RODERICK  IMPEY   MURCHISON $ 

WILLIAM   SMITH,   LL.D 139 

GEORGE  POULETTE   SCROPE,   F.R.S ) 

>      141 
SIR  CHARLES  LYELL,   BART.,  F.R  S ) 

A  LANDSCAPE   AND  MAMMAL   OF   THE   TERTIARY  AGE      ....  143 
A    LANDSCAPE     AND    TERRESTRIAL    REPTILE    OF    THE    MUSOZOIC 

TIME 147 

MANHATTAN    ISLAND    IN     THE    QUATERNARY    AGE — THE    MASTO- 
DON .......      151 

SIR  RICHARD   OWEN 155 

A  METEORIC   STONE 159 

CIRRUS  CLOUDS 163 

CUMULUS  CLOUDS 165 

STRATUS  CLOUDS 168 

JEAN   BAPTISTE  BIOT 178 

LIEUTENANT  MATTHEW  FONTAINE   MAURY  .       .......  179 

A  WHIRLWIND  IN   A  DUSTY  ROAD 188 

WATERSPOUTS  IN  MID-ATLANTIC       .....,,,,,,  18.5 

vi 


DOMINIQUE   FRANCOIS   ARAGO 

}•  201 


ILLUSTRATIONS 

PAGE 

A   SAND-STORM   ON   THE   MOJAVK   DESERT 1£7 

THOMAS  YOUNG      . 195 

HANS   CHRISTIAN   OERSTED -\ 

AUGUSTIN    JEAN    FRESNEL 

JAMES   CLERK   MAXWELL J 

MICHAEL    FARADAY 211 

JAMES  PRESCOTT  JOULE      .... 

WILLIAM   THOMSON    (LORD   KELVIN) 

'  219 
JULIUS    ROBERT   MAYER 

JOHN    TYNDALL      .       .       . 

HERMANN   LUDVVIG   FERDINAND    HELMIIOLTZ 237 

JOHN   DALTON 254 

JOSEPH   LOUIS   GAY-LUSSAC 257 

JOHAN  JAKOB   BERZELIUS 261 

JUSTUS  VON   LIEBIG 267 

ROBERT  WILLIAM   BUNSEN 277 

GUSTAV   ROBERT   KIRCIIHOFF 279 

LOUIS  JACQUES  MANDE  DAGUERRE 281 

JOHN   W.    DRAPER 285 

ERASMUS  DARWIN 290 

JEAN   BAPTISTE   DE  LAMARCK 294 

ETIENNE   GEOFFROY   SAINT-HILAIRE 299 

CHARLES  ROBERT   DARWIN      304 

ALFRED   RUSSELL  WALLACE 308 

THOMAS   HENRY    HUXLEY 311 

ASA  GRAY 314 

ERNEST   HAECKEL 319 

MARIE   FRANCOIS  XAVIER  BICHAT 323 

WILLIAM   HYDE   WOLLASTON 326 

MATTHIAS   JAKOB   SCHLEIDEN 330 

KARL   ERNST   VON   BAER 333 

JOHANNEG   MULLER 337 

WILLIAM  BENJAMIN   CARPENTER 339 

MAX  SCHULTZE 341 

HUGO  VON   MOHL 344 

JEAN   BAPTISTK   DUMAS 346 

vii 


ILLUSTRATIONS 

PAGE 

CLAUDE  BERNARD .  351 

LAENNEC,  INVENTOR  OF  THE  STETHOSCOPE,  AT  THE  NECKER 

HOSPITAL,  PARIS 357 

RUDOLF  VIRCHOW 364 

WILLIAM  T.  G.  MORTON 367 

CRAWFORD  W.  LONG 371 

THEODOR  SCHWANN 377 

SIR  JOSEPH  LISTER , ?'  .  .  .  383 

LOUIS  PASTEUR ,  "«','.  .  .  .  391 

PINEL  AT  LA  SALPETRIERE,  IN  1795,  RELEASING  THE  INSANE 

FROM  THEIR  MANACLES ...  .  .  .  397 

SIR  CHARLES  BELL /  .  .  .  .  402 

FRANgOIS  MAGENDIE 403 

EMIL  DU  BOIS-REYMOND 408 

GUSTAV  THEODOR  FECHNER 413 

JEAN  MARTIN  CHARCOT V  .  *  .  .  .  416 

PAUL  BROCA  ,  421 


THE    STORY    OF    NINETEENTH 
CENTURY    SCIENCE 


THE   STORY   OF   NINETEENTH 
CENTURY   SCIENCE 


CHAPTER   I 
SCIENCE  AT  THE  BEGINNING  OF  THE  CENTURY 


NOT  many  months  ago  word  came  out  of  Germany  of 
a  scientific  discovery  that  startled  the  world.  It  came 
first  as  a  rumor,  little  credited;  then  as  a  pronounced 
report;  at  last  as  a  demonstration.  It  told  of  a  new 
manifestation  of  enej^v,  in  virtue  of  which  the  interior 
of  opaque  objects  is  made  visible  to  human  eyes.  One 
had  only  to  look  into  a  tube  containing  a  screen  of  a  cer- 
tain composition,  and  directed  towards  a  peculiar  electri- 
cal apparatus,  to  acquire  clairvoyant  vision  more  won- 
derful than  the  discredited  second  sight  of  the  medium. 
Coins  within  a  purse,  nails  driven  into  wood,  spectacles 
within  a  leather  case,  became  clearly  visible  when  sub- 
jected to  the  influence  of  this  magic  tube;  and  when  a 
human  hand  was  held  before  the  tube,  its  bones  stood  re- 
vealed in  weird  simplicity,  as  if  the  living,  palpitating  flesh 
about  them  were  but  the  shadowy  substance  of  a  ghost. 

Not  only  could  the  human  eye  see  these  astounding 
revelations,  but  the  impartial  evidence  of  inanimate 


THE   STORY  OF   NINETEENTH-CENTURY  SCIENCE 

chemicals  could  be  brought  forward  to  prove  that  the 
mind  harbored  no  illusion.  The  photographic  film  re- 
corded the  things  that  the  eye  might  see,  and  ghostly 
pictures  galore  soon  gave  a  quietus  to  the  doubts  of  the 
most  sceptical.  Within  a  month  of  the  announcement 
of  Professor  Rontgen's  experiments  comment  upon  the 
"  X  ray  "  and  the  "  new  photography  "  had  become  a 
part  of  the  current  gossip  of  all  Christendom. 

It  was  but  natural  that  thoughtful  minds  should  have 
associated  this  discovery  of  our  boasted  latter-day  epoch 
with  another  discovery  that  was  made  in  the  earliest  in- 
fancy of  our  century.  In  the  year  1801  Mr.  Thomas 
Wedgwood,  of  the  world -renowned  family  of  potters, 
and  Humphry  Davy,  the  youthful  but  already  famous 
chemist,  made  experiments  which  showed  that  it  was 
possible  to  secure  the  imprint  of  a  translucent  body 
upon  a  chemically  prepared  plate  by  exposure  to  sunlight. 
In  this  way  translucent  pictures  were  copied,  and  skela 
tal  imprints  were  secured  of  such  objects  as  leaves  and 
the  wings  of  insects — imprints  strikingly  similar  to  the 
"shadowgraphs"  of  more  opaque  objects  which  we  se- 
cure by  means  of  the  "  new  photography"  to-day.  But 
these  experimenters  little  dreamed  of  the  real  signifi- 
cance of  their  observations.  It  was  forty  years  before 
practical  photography,  which  these  observations  fore- 
shadowed, was  developed  and  made  of  any  use  outside 
the  laboratory. 

It  seems  strange  enough  now  that  imaginative  men — 
and  Davy  surely  was  such  a  man — should  have  paused 
on  the  very  brink  of  so  great  a  discovery.  But  to  harbor 
that  thought  is  to  misjudge  the  nature  of  the  human 
mind.  Things  that  have  once  been  done  seem  easy; 
things  that  have  not  been  done  are  difficult,  though  they 

2 


HUMPHRY  DAVY 
From  the  painting  by  H.  Howard 


SCIENCE   AT   THE   BEGINNING   OF  THE   CENTURY 

lie  but  a  hair's-breadth  off  the  beaten  track.  Who  can 
to-day  foretell  what  revelations  may  be  made,  what  use- 
ful arts  developed,  forty  years  hence  through  the  agency 
of  what  we  now  call  the  new  photography  ? 

It  is  no  part  of  my  purpose,  however,  to  attempt  the 
impossible  feat  of  casting  a  horoscope  for  the  new  pho- 
tography. My  present  theme  is  reminiscent,  not  pro- 
phetic. I  wish  to  recall  what  knowledge  of  the  sciences 
men  had  in  the  days  when  that  discovery  of  Wedgwood 
and  Davy  was  made,  almost  a  hundred  years  ago ;  to 
inquire  what  was  the  scientific  horizon  of  a  person 
standing  at  the  threshold  of  our  own  century.  Let  us 
glance  briefly  at  each  main  department  of  the  science  of 
that  time,  that  we  may  know  whither  men's  minds  were 
trending  in  those  closing  days  of  the  eighteenth  century, 
and  what  were  the  chief  scientific  legacies  of  that  cen- 
tury to  its  successor. 

ii 

In  the  field  of  astronomy  the  central  figure  during 
this  closing  epoch  of  the  eighteenth  century  is  William 
Herschel,  the  Hanoverian,  whom  England  has  made 
hers  by  adoption.  He  is  a  man  with  a  positive  genius 
for  sidereal  discovery.  At  first  a  mere  amateur  in  as- 
tronomy, he  snatches  time  from  his  duties  as  music- 
teacher  to  grind  him  a  telescopic  mirror,  and  begins  gaz- 
ing at  the  stars.  Not  content  with  his  first  telescope, 
he  makes  another,  and  another,  and  he  has  such  genius 
for  the  work  that  he  soon  possesses  a  better  instrument 
than  was  ever  made  before.  His  patience  in  grinding 
the  curved  reflective  surface  is  monumental.  Some- 
times for  sixteen  hours  together  he  must  walk  steadily 
about  the  mirror,  polishing  it,  without  once  removing 

5 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 


JOSIAH    WEDGWOOD 
From  a  painting  by  Sir  Joshua  Reynolds 

his  hands.  Meantime  his  sister,  always  his  chief  lieuten- 
ant, cheers  him  with  her  presence,  and  from  time  to  time 
puts  food  into  his  mouth.  The  telescope  completed,  the 
astronomer  turns  night  into  day,  and  from  sunset  to  sun- 
rise, year  in  and  year  out,  sweeps  the  heavens  unceas- 

6 


SCIENCE  AT  THE   BEGINNING  OF  THE  CENTURY 

ingly,  unless  prevented  by  clouds  or  the  brightness  of 
the  moon.  His  sister  sits  always  at  his  side,  recording 
his  observations.  They  are  in  the  open  air,  perched 
high  at  the  mouth  of  the  reflector,  and  sometimes  it  is 
so  cold  that  the  ink  freezes  in  the  bottle  in  Caroline 
Herschel's  hand  ;  but  the  two  enthusiasts  hardly  notice 
a  thing  so  commonplace  as  terrestrial  weather.  They 
are  living  in  distant  worlds. 

The  results  ?  What  could  they  be  ?  Such  enthusiasm 
would  move  mountains.  But,  after  all,  the  moving  of 
mountains  seems  a  Liliputian  task  compared  with  what 
Herschel  really  does  with  those  wonderful  telescopes. 
He  moves  worlds,  stars,  a  universe — even,  if  you  please, 
a  galaxy  of  universes  ;  at  least  he  proves  that  they 
move,  which  seems  scarcely  less  wonderful ;  and  he 
expands  the  cosmos,  as  man  conceives  it,  to  thousands 
of  times  the  dimensions  it  had  before.  As  a  mere  be- 
ginning, he  doubles  the  diameter  of  the  solar  system 
by  observing  the  great  outlying  planet  which  we  now 
call  Uranus,  but  which  he  christens  Georgium  Sidus, 
in  honor  of  his  sovereign,  and  which  his  French  con- 
temporaries, not  relishing  that  name,  prefer  to  call 
Herschel. 

This  discovery  is  but  a  trifle  compared  with  what  Her- 
schel does  later  on,  but  it  gives  him  world-wide  reputa- 
tion none  the  less.  Comets  and  moons  aside,  this  is  the 
first  addition  to  the  solar  system  that  has  been  made 
within  historic  times,  and  it  creates  a  veritable  furor  of 
popular  interest  and  enthusiasm.  Incidentally  King 
George  is  flattered  at  having  a  world  named  after  him, 
and  he  smiles  on  the  astronomer,  and  comes  with  his 
court  to  have  a  look  at  his  namesake.  The  inspection 
is  highly  satisfactory  ;  and  presently  the  royal  favor 

7 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

enables  the  astronomer  to  escape  the  thraldom  of  teach- 
ing music,  and  to  devote  his  entire  time  to  the  more  con- 
genial task  of  star-gazing. 

Thus  relieved  from  the  burden  of  mundane  embarrass- 
ments, he  turns  with  fresh  enthusiasm  to  the  skies,  and 
his  discoveries  follow  one  another  in  bewildering  profu- 
sion. He  finds  various  hitherto  unseen  moons  of  our 
sister  planets ;  he  makes  special  studies  of  Saturn,  and 
proves  that  this  planet,  with  its  rings,  revolves  on  its 
axis ;  he  scans  the  spots  on  the  sun,  and  suggests  that 
they  influence  the  weather  of  our  earth;  in  short,  he 
extends  the  entire  field  of  solar  astronomy.  But  very 
soon  this  field  becomes  too  small  for  him,  and  his  most 
important  researches  carry  him  out  into  the  regions  of 
space  compared  with  which  the  span  of  our  solar  system 
is  a  mere  point.  With  his  perfected  telescopes  he  enters 
abysmal  vistas  which  no  human  eye  ever  penetrated  be- 
fore, which  no  human  eye  had  hitherto  more  than  vague- 
ly imagined.  He  tells  us  that  his  forty-foot  reflector 
will  bring  him  light  from  a  distance  of  "  at  least  eleven 
and  three-fourths  millions  of  millions  of  millions  of 
miles" — light  which  left  its  source  two  million  years 
ago.  The  smallest  stars  visible  to  the  unaided  eye  are 
those  of  the  sixth  magnitude  ;  this  telescope,  he  thinks, 
has  power  to  reveal  stars  of  the  1342d  magnitude. 

But  what  does  Herschel  learn  regarding  these  awful 
depths  of  space  and  the  stars  that  people  them  ?  That 
is  what  the  world  wishes  to  know.  Copernicus,  Galileo, 
Kepler,  have  given  us  a  solar  system,  but  the  stars  have 
been  a  mystery.  What  says  the  great  reflector — are  the 
stars  points  of  light,  as  the  ancients  taught,  and  as  more 
than  one  philosopher  of  the  eighteenth  century  has  still 
contended^  or  are  they  suns,  as  others  hold  ?  HerscheJ 

8 


HERSCHEL   AND  HIS  SISTER  AT  THE  TELESCOPE 


OF    THti 

UNIVERSITY 
•ft* 


SCIENCE  AT  THE  BEGINNING  OF  THE  CENTURY 

answers,  they  are  suns,  each  and  every  one  of  all  the 
millions — suns,  many  of  them,  larger  than  the  one  that 
is  the  centre  of  our  tiny  system.  Not  only  so,  but  they 
are  moving  suns.  Instead  of  being  fixed  in  space,  as  has 
been  thought,  they  are  whirling  in  gigantic  orbits  about 
some  common  centre.  Is  our  sun  that  centre?  Far  from 
it.  Our  sun  is  only  a  star,  like  all  the  rest,  circling  on 
with  its  attendant  satellites — our  giant  sun  a  star,  no 
different  from  myriad  other  stars,  not  even  so  large  as 
some ;  a  mere  insignificant  spark  of  matter  in  an  infinite 
shower  of  sparks. 

Nor  is  this  all.  Looking  beyond  the  few  thousand 
stars  that  are  visible  to  the  naked  eye,  Herschel  sees 
series  after  series  of  more  distant  stars,  marshalled  in 
galaxies  of  millions  ;  but  at  last  he  reaches  a  distance 
beyond  which  the  galaxies  no  longer  increase.  And  yet 
— so  he  thinks — he  has  not  reached  the  limits  of  his  vi- 
sion. What  then  ?  He  has  come  to  the  bounds  of  the 
sidereal  system  ;  seen  to  the  confines  of  the  universe. 
He  believes  that  he  can  outline  this  system,  this  universe, 
and  prove  that  it  has  the  shape  of  an  irregular  globe, 
oblately  flattened  to  almost  disklike  proportions,  and  di- 
vided at  one  edge — a  bifurcation  that  is  revealed  even  to 
the  naked  eye  in  the  forking  of  the  Milky  Way. 

This,  then,  is  our  universe  as  Herschel  conceives  it — a 
vast  galaxy  of  suns,  held  to  one  centre,  revolving,  poised 
in  space.  But  even  here  those  marvellous  telescopes  do 
not  pause.  Far,  far  out  beyond  the  confines  of  our  uni- 
verse, so  far  that  the  awful  span  of  our  own  system 
might  serve  as  a  unit  of  measure,  are  revealed  other  sys- 
tems, other  universes,  like  our  own,  each  composed,  as 
he  thinks,  of  myriads  of  suns,  clustered  like  our  galaxy 
into  an  isolated  system — mere  islands  of  matter  in  an 

11 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

infinite  ocean  of  space.  So  distant  from  our  universe 
are  these  ne\v  universes  of  Herschel's  discovery  that 
their  light  reaches  us  only  as  a  dim  nebulous  glow,  in 
most  cases  invisible  to  the  unaided  eye.  About  a  hundred 
of  these  nebulae  were  known  when  Herschel  began  his 
studies.  Before  the  close  of  the  century  he  has  discov- 
ered about  two  thousand  more  of  them,  and  many  of  these 
had  been  resolved  by  his  largest  telescopes  into  clusters 
of  stars.  He  believes  that  the  farthest  of  these  nebulas 
that  he  can  see  is  at  least  300,000  times  as  distant  from 
us  as  the  nearest  fixed  star.  Yet  that  nearest  star  is  so 
remote  that  its  light,  travelling  180,000  miles  a  second, 
requires  three  and  one-half  years  to  reach  our  planet. 

As  if  to  give  the  finishing- touches  to  this  novel 
scheme  of  cosmology,  Herschel,  though  in  the  main 
very  little  given  to  unsustained  theorizing,  allows  him- 
self the  privilege  of  one  belief  that  he  cannot  call  upon 
his  telescopes  to  substantiate.  He  thinks  that  all  the 
myriad  suns  of  his  numberless  systems  are  instinct  with 
life  in  the  human  sense.  Giordano  Bruno  and  a  long 
line  of  his  followers  had  held  that  some  of  our  sister 
planets  may  be  inhabited,  but  Herschel  extends  the 
thought  to  include  the  moon,  the  sun,  the  stars — all  the 
heavenly  bodies.  He  believes  that  he  can  demonstrate 
the  habitability  of  our  own  sun,  and  reasoning  from 
analogy,  he  is  firmly  convinced  that  all  the  suns  of  all 
the  systems  are  "  well  supplied  with  inhabitants."  In 
this,  as  in  some  other  inferences,  Herschel  is  misled  by 
the  faulty  physics  of  his  time.  Future  generations,  work- 
ing with  perfected  instruments,  may  not  sustain  him 
all  along  the  line  of  his  observations  even,  let  alone  his 
inferences.  But  how  one's  egotism  shrivels  and  shrinks 
as  one  grasps  the  import  of  his  sweeping  thoughts ! 

12 


SCIENCE  AT  THE   BEGINNING  OF  THE  CENTURY 

Continuing  his  observations  of  the  innumerable  nebu- 
lae, Herschel  is  led  presently  to  another  curious  specula- 
tive inference.  He  notes  that  some  star  groups  are  much 
more  thickly  clustered  than  others,  and  he  is  led  to  in- 
fer that  such  varied  clustering  tells  of  varying  ages  of 
the  different  nebulae.  He  thinks  that  at  first  all  space 
may  have  been  evenly  sprinkled  with  the  stars,  and  that 
the  grouping  has  resulted  from  the  action  of  gravita- 
tion. Looking  forward,  it  appears  that  the  time  must 
come  when  all  the  suns  of  a  system  will  be  drawn  to- 
gether and  destroyed  by  impact  at  a  common  centre. 
Already,  it  seems  to  him,  the  thickest  clusters  have 
"  outlived  their  usefulness,"  and  are  verging  towards 
their  doom. 

But  again,  other  nebulae  present  an  appearance  sug- 
gestive of  an  opposite  condition.  They  are  not  resolva- 
able  into  stars,  but  present  an  almost  uniform  appear- 
ance throughout,  and  are  hence  believed  to  be  composed 
of  a  shining  fluid,  which  in  some  instances  is  seen  to  be 
condensed  at  the  centre  into  a  glowing  mass.  In  such 
a  nebula  Herschel  thinks  he  sees  a  sun  in  process  of 
formation. 

Taken  together,  these  two  conceptions  outline  a  ma- 
jestic cycle  of  world  formation  and  world  destruction— 
a  broad  scheme  of  cosmogony,  such  as  had  been  vaguely 
adumbrated  two  centuries  before  by  Kepler,  and  in 
more  recent  times  by  "Wright  and  Kant  and  Sweden- 
borg.  This  so-called  "nebular  hypothesis"  assumes 
that  in  the  beginning  all  space  was  uniformly  filled 
with  cosmic  matter  in  a  state  of  nebular  or  "  fire-mist " 
diffusion,  "  formless  and  void."  It  pictures  the  con- 
densation— coagulation,  if  you  wil\ — of  portions  of  this 
mass  to  form  segregated  masses,  a  td  the  ultimate  devel- 

13 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

opment  out  of  these  masses  of  the  sidereal  bodies  which 
•  we  see.  Thus  far  the  mind  follows  readily;  but  now 
come  difficulties.  How  happens  it,  for  example,  that 


JAMES  LOUIS  LAGRANGE 

the  cosmic  mass  from  which  was  born  our  solar  system 
was  divided  into  several  planetary  bodies  instead  of  re- 
maining a  single  mass?  Were  the  planets  struck  off 
from  the  sun  by  the  chance  impact  of  comets,  as  Buffon 

14 


SCIENCE  AT  THE   BEGINNING  OF  THE  CENTURY 

has  suggested  ?  or  thrown  out  by  explosive  volcanic  ac- 
tion, in  accordance  with  the  theory  of  Dr.  Darwin  ?  or 
do  they  owe  their  origin  to  some  unknown  law  ?  In 
any  event,  how  chanced  it  that  all  were  projected  in 
nearly  the  same  plane  as  we  now  find  them  ? 

It  remained  for  a  mathematical  astronomer  to  solve 
these  puzzles.  The  man  of  all  others  competent  to  take 
the  subject  in  hand  was  the  French  astronomer  Laplace. 
For  a  quarter  of  a  century  he  had  devoted  his  transcen- 
dent mathematical  abilities  to  the  solution  of  problems 
of  motion  of  the  heavenly  bodies.  Working  in  friendly 
rivalry  with  his  countryman  Lagrange,  his  only  peer 
among  the  mathematicians  of  the  age,  he  had  taken  up 
and  solved  one  by  one  the  problems  that  Newton  left 
obscure.  Largely  through  the  efforts  of  these  two  men 
the  last  lingering  doubts  as  to  the  solidarity  of  the  New- 
tonian hypothesis  of  universal  gravitation  had  been  re- 
moved. The  share  of  Lagrange  was  hardly  less  than 
that  of  his  co-worker ;  but  Lagrange  will  longer  be  re- 
membered, because  he  ultimately  brought  his  completed 
labors  into  a  system,  and  incorporating  with  them  the 
labors  of  his  contemporaries,  produced  in  the  Mecanique 
Celeste  the  undisputed  mathematical  monument  of  the 
century,  a  fitting  complement  to  the  Principia  of  New- 
ton, which  it  supplements  and  in  a  sense  completes. 

In  the  closing  years  of  the  century  Laplace  takes  up 
the  nebular  hypothesis  of  cosmogony,  to  which  we  have 
just  referred,  and  gives  it  definitive  proportions;  in  fact, 
makes  it  so  thoroughly  his  own  that  posterity  will  al- 
ways link  it  with  his  name.  Discarding  the  crude  no- 
tions of  cometary  impact  and  volcanic  eruption,  Laplace 
fills  up  the  gaps  in  the  hypothesis  with  the  aid  only  of 
well-known  laws  of  gravitation  and  motion.  He  assumes 

15 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

that  the  primitive  mass  of  cosmic  matter  which  was 
destined  to  form  our  solar  system  was  revolving  on  its 
axis  even  at  a  time  when  it  was  still  nebular  in  charac- 
ter, and  filled  all  space  to  a  distance  far  beyond  the 
present  limits  of  the  system.  As  this  vaporous  mass 
contracted  through  loss  of  heat,  it  revolved  more  and 
more  swiftly,  and  from  time  to  time,  through  balance 
of  forces  at  its  periphery,  rings  of  its  substance  were 
whirled  off  and  left  revolving  there,  to  subsequently 
become  condensed  into  planets,  and  in  their  turn  whirl 
off  minor  rings  that  became  moons.  The  main  body  of 
the  original  mass  remains  in  the  present  as  the  still  con- 
tracting and  rotating  body  which  we  call  the  sun. 

The  nebular  hypothesis  thus  given  detailed  comple- 
tion by  Laplace  is  a  worthy  complement  of  the  grand 
cosmologic  scheme  of  Herschel.  Whether  true  or  false, 
the  two  conceptions  stand. as  the  final  contributions  of 
the  eighteenth  century  to  the  history  of  man's  ceaseless 
efforts  to  solve  the  mysteries  of  cosmic  origin  and  cosmic 
structure.  The  world  listens  eagerly  and  without  preju- 
dice to  the  new  doctrines;  and  that  attitude  tells  of  a 
marvellous  intellectual  growth  of  our  race.  Mark  the 
transition.  In  the  year  1600,  Bruno  was  burned  at  the 
stake  for  teaching  that  our  earth  is  not  the  centre  of  the 
universe.  In  1700,  Newton  was  pronounced  "impious 
and  heretical"  by  a  large  school  of  philosophers  for 
declaring  that  the  force  which  holds  the  planets  in  their 
orbits  is  universal  gravitation.  In  1800,  Laplace  and 
Herschel  are  honored  for  teaching  that .  gravitation 
built  up  the  system  which  it  still  controls ;  that  our 
universe  is  but  a  minor  nebula,  our  sun  but  a  minor  star, 
our  earth  a  mere  atom  of  matter,  our  race  only  one  of 
myriad  races  peopling  an  infinity  of  worlds.  Doctrines 

J6 


SCIENCE  AT  THE   BEGINNING  OF  THE  CENTURY 

which  but  the  span  of  two  human  lives  before  would 
have  brought  their  enunciators  to  the  stake  were  now 
pronounced  not  impious,  but  sublime. 


in 

One  might  naturally  suppose  that  the  science  of  the 
earth,  which  lies  at  man's  feet,  would  at  least  have  kept 
pace-  with  the  science  of  distant  stars.  But  perhaps  the 
very  obviousness  of  the  phenomena  delayed  the  study 
of  the  crust  of  the  earth.  It  is  the  unattainable  that 
allures  and  mystifies  and  enchants  the  developing  mind. 
The  proverbial  child  spurns  its  toys  and  cries  for  the 
moon. 

So  in  those  closing  days  of  the  eighteenth  centurj^ 
when  astronomers  had  gone  so  far  towards  explaining 
the  mysteries  of  the  distant  portions  of  the  universe, 
we  find  a  chaos  of  opinion  regarding  the  structure  and 
formation  of  the  earth.  Guesses  were  not  wanting  to 
explain  the  formation  of  tl^A*rld,  it  is  true,  but,  with 
one  or  two  exceptions,  thd^R  bizarre  indeed.  One 
theory  supposed  the  earth^onave  been  at  first  a  solid 
mass  of  ice,  which  became  animated  only  after  a  comet 
had  dashed  against  it.  Other  theories  conceived  the 
original  globe  as  a  mass  of  water,  over  which  floated 
vapors  containing  the  solid  elements,  which  in  due  time 
were  precipitated  as  a  crust  upon  the  waters.  In  a 
word,  the  various  schemes  supposed  the  original  mass  to 
have  been  ice,  or  water,  or  a  conglomerate  of  water  and 
solids,  according  to  the  random  fancies  of  the  theorists ; 
and  the  final  separation  into  land  and  water  was  con- 
ceived to  have  taken  place  in  all  the  ways  which  fancy, 
quite  unchecked  by  any  tenable  data,  could  invent. 

B  17 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 


JAMES    HUTTON 


Whatever  important  changes  in  the  general  character 
of  the  surface  of  the  globe  were  conceived  to  have  taken 
place  since  its  creation  were  generally  associated  with 
the  Mosaic  deluge,  and  the  theories  which  attempted  to 
explain  this  catastrophe  were  quite  on  a  par  with  those 
which  dealt  with  a  remoter  period  of  the  earth's  history. 

18 


SCIENCE  AT  THE   BEGINNING  OF  THE  CENTURY 

Some  speculators,  holding  that  the  interior  of  the  globe 
is  a  great  abyss  of  waters,  conceived  that'  the  crust  had 
dropped  into  this  chasm  and  had  thus  been  inundated. 
Others  held  that  the  earth  had  originally  revolved  on 
a  vertical  axis,  and  that  the  sudden  change  to  its  pres- 
ent position  had  caused  the  catastrophic  shifting  of 
its  oceans.  But  perhaps  the  favorite  theory  was  that 
which  supposed  a  comet  to  have  wandered  near  the 
earth,  and  in  whirling  about  it  to  have  carried  the  wa- 
ters, through  gravitation,  in  a  vast  tide  over  the  conti- 
nents. 

Thus  blindly  groped  the  majority  of  eighteenth-cen- 
tury philosophers  in  their  attempts  to  study  what  we 
now  term  geology.  Deluded  by  the  old  deductive 
methods,  they  founded  not  a  science,  but  the  ghost  of  a 
science,  as  immaterial  and  as  unlike  anything  in  nature 
as  any  other  phantom  that  could  be  conjured  from  the 
depths  of  the  speculative  imagination.  And  all  the  while 
the  beckoning  earth  lay  beneath  the  feet  of  these  vision- 
aries ;  but  their  eyes  were  fixed  in  air. 

At  last,  however,  there  came  a  man  who  had  the 
penetration  to  see  that  the  phantom  science  of  geology 
needed  before  all  else  a  body  corporeal,  and  who  took  to 
himself  the  task  of  supplying  it.  This  was  Dr.  James 
Hutton,  of  Edinburgh,  physician,  farmer,  and  manufact- 
uring chemist;  patient,  enthusiastic, level-headed  devotee 
of  science.  Inspired  by  his  love  of  chemistry  to  study 
the  character  of  rocks  and  soils,  Hutton  had  not  gone  far 
before  the  earth  stood  revealed  to  him  in  a  new  light. 
He  saw,  what  generations  of  predecessors  had  blindly 
refused  to  see,  that  the  face  of  nature  everywhere, 
instead  of  being  rigid  and  immutable,  is  perennially 
plastic,  and  year  by  year  is  undergoing  metamorphic 

19 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

changes.  The  solidest  rocks  are  day  by  day  disinte- 
grated, slowly,  but  none  the  less  surely,  by  wind  and 
rain  and  frost,  by  mechanical  attrition  and  chemical 
decomposition,  to  form  the  pulverized  earth  and  clay. 
This  soil  is  being  swept  away  by  perennial  showers,  and 
carried  off  to  the  oceans.  The  oceans  themselves  beat 
on  their  shores,  and  eat  insidiously  into  the  structure  of 
sands  and  rocks.  Everywhere,  slowly  but  surely,  the 
surface  of  the  land  is  being  worn  away;  its  substance  is 
being  carried  to  burial  in  the  seas. 

Should  this  denudation  continue  long  enough,  thinks 
Hutton,  the  entire  surface  of  the  continents  must  be 
worn  away.  Should  it  be  continued  long  enough!  And 
with  that  thought  there  flashes  on  his  mind  an  inspiring 
conception— the  idea  that  solar  time  is  long,  indefinitely 
long.  That  seems  a  simple  enough  thought — almost  a 
truism — to  the  nineteenth-century  mind  ;  but  it  required 
genius  to  conceive  it  in  the  eighteenth.  Plutton  pon- 
dered it,  grasped  its  full  import,  and  made  it  the  basis  of 
his  hypothesis,  his  "  theory  of  the  eartlv' 

The  hypothesis  is  this — that  the  observed  changes 
of  the  surface  the  earth,  continued  through  indefinite 
lapses  of  time,  must  result  in  conveying  all  the  land  at 
last  to  the  sea;  in  wearing  continents  away  till  the 
oceans  overflo\v  them.  What  then  ?  Whv,  as  the  con- 
tinents wear  down,  the  oceans  are  filling  up.  Along 
their  bottoms  the  detritus  of  wasted  continents  is  de- 
posited in  strata,  together  with  the  bodies  of  marine 
animals  and  vegetables.  Why  might  not  this  debris 
solidify  to  form  layers  of  rocks — the  basis  of  new  con- 
tinents ?  Why  not,  indeed  ? 

But  have  we  any  proof  that  such  formation  of  rocks 
in  an  ocean-bed  has,  in  fact,  occurred  ?  To  be  sure  we 

20 


SCIENCE  AT  THE   BEGINNING  OF  THE  CENTURY 

have.  It  is  furnished  by  every  bed  of  limestone,  every 
outcropping  fragment  of  fossil-bearing  rock,  every  strati- 
fied cliff.  How  else  than  through  such  formation,  in  an 
ocean-bed  came  these  rocks  to  be  stratified  ?  How  else 
came  they  to  contain  the  shells  of  once  living  organisms 
embedded  in  their  depths?  The  ancients,  finding  fossil 
shells  embedded  in  the  rocks,  explained  them  as  mere 
freaks  of  u  nature  and  the  stars."  Less  superstitious 
generations  had  repudiated  this  explanation,  but  had 
failed  to  give  a  tenable  solution  of  the  mystery.  To 
Hutton  it  is  a  mystery  no  longer.  To  him  it  seems 
clear  that  the  basis  of  the  present  continents  was  laid  in 
ancient  sea-beds,  formed  of  the  detritus  of  continents 
yet  more  ancient. 

But  two  links  are  still  wanting  to  complete  the  chain 
of  Hutton's  hypothesis.  Through  what  agency  has  the 
ooze  of  the  ocean-bed  been  transformed  into  solid  rock  ? 
And  through  what  agency  has  this  rock  been  lifted 
above  the  surface  of  the  water,  to  form  new  continents  ? 
Hutton  looks  about  him  for  a  clew,  and  soon  he  finds 
it.  Everywhere  about  us  there  are  outcropping  rocks 
that  are  not  stratified,  but  which  give  evidence  to  the 
observant  eye  of  having  once  been  in  a  molten  state. 
Different  minerals  are  mixed  together;  pebbles  are 
scattered  through  masses  of  rock  like  plums  in  a  pud- 
ding; irregular  crevices  in  otherwise  solid  masses  of 
rock — so-called  veinings— are  seen  to  be  filled  with 
equally  solid  granite  of  a  different  variety,  which  can 
have  gotten  there  in  no  conceivable  way,  so  Hutton 
thinks,  but  by  running  in  while  molten,  as  liquid  metal 
is  run  into  the  moulds  of  the  founder.  Even  the  strati- 
fied rocks,  though  they  seemingly  have  not  been  melted, 
give  evidence  in  some  instances  of  having  been  sub- 

21 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

jected  to  the  action  of  heat.  Marble,  for  example,  is 
clearly  nothing  but  calcined  limestone. 

With  such  evidence  before  him,  Hutton  is  at  no  loss 
to  complete  his  hypothesis.  The  agency  which  has  solid- 
ified the  ocean-beds,  he  says,  is  subterranean  heat.  The 
same  agency,  acting  excessively,  has  produced  volcanic 
cataclysms,  upheaving  ocean-beds  to  form  continents. 
The  rugged  and  uneven  surfaces  of  mountains,  the  tilted 
and  broken  character  of  stratified  rocks  everywhere,  are 
the  standing  witnesses  of  these  gigantic  upheavals. 

And  with  this  the  imagined  cycle  is  complete.  The 
continents,  worn  away  and  carried  to  the  sea  by  the  action 
of  the  elements,  have  been  made  over  into  rocks  again 
in  the  ocean-beds,  and  then  raised  once  more  into  conti- 
nents. And  this  massive  cycle,  in  Hutton's  scheme,  is 
supposed  to  have  occurred  not  once  only,  but  over  and 
over  again,  times  without  number.  In  this  unique  view 
ours  is  indeed  a  world  without  beginning  and  without 
end;  its  continents  have  been  making  and  unmaking  in 
endless  series  since  time  began. 

Hutton  formulated  his  hypothesis  while  yet  a  young 
man,  not  long  after  the  middle  of  the  century.  He 
lirst  gave  it  publicity  in  1781,  in  a  paper  before  the 
Royal  Societ}^  of  Edinburgh,  a  paper  which  at  the  mo- 
ment neither  friend  nor  foe  deigned  to  notice.  It  was 
not  published  in  book  form  till  the  last  decade  of  the 
century,  when  Hutton  had  lived  with  and  worked  over 
his  theory  for  almost  fifty  years.  Then  it  caught  the 
eye  of  the  world.  A  school  of  followers  expounded  the 
Huttonian  doctrines;  a  rival  school,  under  Werner,  in 
Germany,  opposed  some  details  of  the  hypothesis ;  and 
the  educated  world  as  a  whole  viewed  disputants 
askance.  The  very  novelty  of  the  new  views  forbade  their 

22 


SCIENCE  AT  THE  BEGINNING  OF  THE  CENTURY 

immediate  acceptance.  Bitter  attacks  were  made  upon 
the  "  heresies,"  and  that  was  meant  to  be  a  soberly  tem- 
pered judgment  which  in  1800  pronounced  Hutton's 
theories  "  not  only  hostile  to  sacred  history,  but  equally 
hostile  to  the  principles  of  probability,  to  the  results  of 
the  ablest  observations  on  the  mineral  kingdom,  and  to 
the  dictates  of  rational  philosophy."  And  all  this  be- 
cause Hutton's  theory  presupposed  the  earth  to  have 
been  in  existence  more  than  six  thousand  years. 

Thus  it  appears  that  though  the  thoughts  of  men  had 
widened,  in  these  closing  days  of  the  eighteenth  cen- 
tury, to  include  the  stars,  they  had  not  as  yet  expanded 
to  receive  the  most  patent  records  that  are  written 
everywhere  on  the  surface  of  the  earth.  Before  Hut- 
ton's  views  could  be  accepted,  his  pivotal  conception 
that  time  is  long  must  be  established  by  convincing 
proofs.  The  evidence  was  being  gathered  by  William 
Smith,  Cuvier,  and  other  devotees  of  the  budding  science 
of  paleontology  in  the  last  days  of  the  century,  but  the 
record  of  their  completed  labors  belongs  to  another 
epoch. 

IV 

The  eighteenth  -  century  philosopher  made  great 
strides  in  his  studies  of  the  physical  properties  of  mat- 
ter, and  the  application  of  these  properties  in  mechan- 
ics, as  the  steam-engine,  the  balloon,  the  optic  telegraph, 
the  spinning-jenny,  the  cotton-gin,  the  chronometer,  the 
perfected  compass,  the  Ley  den  jar,  the  lightning-rod, 
and  a  host  of  minor  inventions  testify.  In  a  speculative 
way  he  had  thought  out  more  or  less  tenable  concep- 
tions as  to  the  ultimate  nature  of  matter,  as  witness  the 
theories  of  Leibnitz  and  Boscovich  and  Davy,  to  which 

23 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

we  may  recur.  But  he  had  not  as  yet  conceived  the 
notion  of  a  distinction  between  matter  and  energy, 
which  is  so  fundamental  to  the  physics  of  a  later  epoch. 
He  did  not  speak  of  heat,  light,  electricity,  as  forms  of 
energy  or  "force";  he  conceived  them  as  subtile  forms 
of  matter — as  highly  attenuated  yet  tangible  fluids,  sub- 
ject to  gravitation  and  chemical  attraction ;  though  he 
had  learned  to  measure  none  of  them  but  heat  with  ac- 
curacy, and  this  one  he  could  test  only  within  narrow 
limits  until  late  in  the  century,  when  Josiah  Wedgwood, 
the  famous  potter,  taught  him  to  gauge  the  highest  tem- 
peratures with  the  clay  pyrometer. 

He  spoke  of  the  matter  of  heat  as  being  the  most  uni- 
versally distributed  fluid  in  nature;  as  entering  in  some 
degree  into  the  composition  of  nearly  all  other  sub- 
stances ;  as  being  sometimes  liquid,  sometimes  con- 
densed or  solid,  and  as  having  weight  that  could  be  de- 
tected with  the  balance.  Following  Newton,  he  spoke 
of  light  as  a  "  corpuscular  emanation  "  or  fluid,  composed 
of  shining  particles  which  possibly  are  transmutable 
into  particles  of  heat,  and  which  enter  into  chemical 
combination  with  the  particles  of  other  forms  of  matter. 
Electricity  he  considered  a  still  more  subtile  kind  of  mat- 
ter— perhaps  an  attenuated  form  of  light.  Magnetism, 
"  vital  fluid,"  and  by  some  even  a  "  gravic  fluid,"  and  a 
fluid  of  sound,  were  placed  in  the  same  scale  ;  and  taken 
together,  all  these  supposed  subtile  forms  of  matter  were 
classed  as  "  imponderables." 

This  view  of  the  nature  of  the  "  imponderables  "  was 
in  some  measure  a  retrogression,  for  many  seventeenth- 
century  philosophers,  notably  Hooke  and  Huygens  and 
Boyle,  had  held  more  correct  views ;  but  the  materi- 
alistic conception  accorded  so  well  with  the  eighteen th- 

24 


SCIENCE  AT  THE   BEGINNING  OF  THE  CENTURY 

century  tendencies  of  thought  that  only  here  and  there 
a  philosopher,  like  Euler,  called  it  in  question,  until  well 
on  towards  the  close  of  the  century.  Current  speech  re- 
ferred to  the  materiality  of  the  "imponderables"  un- 
iquestioningly.  Students  of  meteorology — a  science  that 
was  just  dawning — explained  atmospheric  phenomena 


BENJAMIN    THOMPSON— COUNT   KUMFORD 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

on  the  supposition  that  heat,  the  heaviest  imponderable, 
predominated  in  the  lower  atmosphere,  and  that  light, 
electricity,  and  magnetism  prevailed  in  successively 
higher  strata,  And  Lavoisier,  the  most  philosophical 
chemist  of  the  century,  retained  heat  and  light  on  a  par 
with  oxygen,  hydrogen,  iron,  and  the  rest,  in  his  list  of 
elementary  substances. 

But  just  at  the  close  of  the  century  the  confidence  in 
the  status  of  the  imponderables  was  rudely  shaken  in 
the  minds  of  philosophers  by  the  revival  of  the  old  idea 
of  Fra  Paolo  and  Bacon  and  Boyle,  that  heat,  at  any 
rate,  is  not  a  material  fluid,  but  merely  a  mode  of  mo- 
tion or  vibration  among  the  particles  of  "ponderable" 
matter.  The  new  champion  of  the  old  doctrine  as  to 
the  nature  of  heat  was  a  very  distinguished  philosopher 
and  diplomatist  of  the  time,  who,  it  may  be  worth  re- 
calling, was  an  American.  He  was  a  sadly  expatriated 
American,  it  is  true,  as  his  name,  given  all  the  official 
appendages,  will  amply  testify ;  but  he  had  been  born 
and  reared  in  a  Massachusetts  village  none  the  less,  and 
he  seems  always  to  have  retained  a  kindly  interest  in 
the  land  of  his  nativity,  even  though  he  lived  abroad  in 
the  service  of  other  powers  during  all  the  later  years  of 
his  life,  and  was  knighted  by  England,  ennobled  by  Ba- 
varia, and  honored  by  the  most  distinguished  scientific 
bodies  of  Europe.  The  American,  then,  who  cham- 
pioned the  vibratory  theory  of  heat,  in  opposition  to  all 
current  opinion,  in  this  closing  era  of  the  eighteenth 
century,  was  Lieutenant-General  Sir  Benjamin  Thomp- 
son, Count  Rumford,  F.  R.  S. 

Rumford  showed  that  heat  may  be  produced  in  in- 
definite quantities  by  friction  of  bodies  that  do  not 
themselves  lose  any  appreciable  matter  in  the  process, 

26 


SCIENCE  AT  THE  BEGINNING  OF  THE  CENTURY 

and  claimed  that  this  proves  the  immateriality  of  heat. 
Later  on  he  added  force  to  the  argument  by  proving,  in 
refutation  of  the  experiments  of  Bowditch,  that  no  body 
either  gains  or  loses  weight  in  virtue  of  being  heated 
or  cooled.  He  thought  it  proved  that  heat  is  only  a 
mode  of  motion. 

But  contemporary  judgment,  while  it  listened  respect- 
fully to  Rumford,  was  little  minded  to  accept  his  ver- 
dict. The  cherished  beliefs  of  a  generation  are  not  to 
be  put  down  with  a  single  blow.  Where  many  minds 
have  a  similar  drift,  however,  the  first  blow  may  precip- 
itate a  general  conflict ;  and  so  it  was  here.  Young 
Humphry  Davy  had  duplicated  Rumford's  experiments, 
and  reached  similar  conclusions ;  and  soon  others  fell 
into  line.  Then,  in  1800,  Dr.  Thomas  Young— "Phe- 
nomenon Young  "  they  called  him  at  Cambridge,  because 
he  was  reputed  to  know  everything — took  up  the  cud- 
gels for  the  vibratory  theory  of  light,  and  it  began  to 
be  clear  that  the  two  "imponderables,"  heat  and  light, 
must  stand  or  fall  together ;  but  no  one  as  yet  made  a 
claim  against  the  fluidity  of  electricity. 

But  before  this  speculative  controversy  over  the  nat- 
ure of  the  "imponderables"  had  made  more  than  a  fair 
beginning,  in  the  last  year  of  the  century,  a  discovery 
was  announced  which  gave  a  new  impetus  to  physical 
science,  and  for  the  moment  turned  the  current  of  spec- 
ulation into  another  channel.  The  inventor  was  the 
Italian  scientist  Yolta ;  his  invention,  the  apparatus  to 
be  known  in  future  as  the  voltaic  pile — the  basis  of  the 
galvanic  battery.  Ten  years  earlier  Galvani  had  discov- 
ered that  metals  placed  in  contact  have  the  power  to 
excite  contraction  in  the  muscles  of  animals  apparently 
dead.  Working  along  lines  suggested  by  this  discovery, 

27 


THE  STORY  OF  NINCTEE  NTH-CENTURY  SCIENCE 

Yolta  developed  an  apparatus  composed  of  two  metals 
joined  together  and  acted  on  by  chemicals,  which  ap- 
peared to  accumulate  or  store  up  the  galvanic  influence, 
whatever  it  might  be.  The  effect  could  be  accentuated 
by  linking  together  several  such  "  piles "  into  a  "  bat- 
tery." 

This  invention  took  the  world  by  storm.  Nothing 
like  the  enthusiasm  it  created  in  the  philosophic  world 
had  been  known  since  the  invention  of  the  Ley  den  jar, 
more  than  half  a  century  before.  Within  a  few  weeks 
after  Yolta's  announcement,  batteries  made  according 
to  his  plan  were  being  experimented  with  in  every  im- 
portant laboratory  in  Europe.  The  discovery  was  made 
in  March.  Early  in  May  two  Englishmen,  Messrs. 
Nicholson  and  Carlyle,  practising  with  the  first  battery 
made  in  their  country,  accidentally  discovered  the  de- 
composition of  water  by  the  action  of  the  pile.  And 
thus  in  its  earliest  infancy  the  new  science  of  "  galvan- 
ism "  had  opened  the  way  to  another  new  science — elec- 
tro-chemistry. 

As  the  century  closed,  half  the  philosophic  world  was 
speculating  as  to  whether  "  galvanic  influence  "  were  a 
new  imponderable  or  only  a  form  of  electricity  ;  and  the 
other  half  was  eagerly  seeking  to  discover  what  new 
marvels  the  battery  might  reveal.  The  least  imagina- 
tive man  could  see  that  here  was  an  invention  that 
would  be  epoch-making,  but  the  most  visionary  dreamer 
could  not  even  vaguely  adumbrate  the  real  measure  of 
its  importance.  Hitherto  electricity  had  been  only  a 
laboratory  aid  or  a  toy  of  science,  with  no  suggestion  of 
practical  utility  beyond  its  doubtful  application  in  medi- 
cine ;  in  future,  largely  as  the  outgrowth  of  Yolta's  dis- 
covery, it  was  destined  to  become  a  great  economic 

28 


SCIENCE  AT  THE   BEGINNING  OF  THE  GENTUHY 

agency,  whose  limitations  not  even  the  enlarged  vision 
of  our  later  century  can  pretend  to  outline. 


Of  all  the  contests  that  were  waging  in  the  various 
fields  of  science  in  this  iconoclastic  epoch,  perhaps  the 
fiercest  and  most  turbulent  was  that  which  fell  within 
the  field  of  chemistry.  Indeed,  this  was  one  of  the 
most  memorable  warfares  in  the  history  of  polemics.  It 
was  a  battle  veritably  Napoleonic  in  its  inception,  scope, 
and  incisiveness.  As  was  fitting,  it  was  a  contest  of 
France  against  the  world ;  but  the  Napoleonic  parallel 
fails  before  the  end,  for  in  this  case  France  won  not 
only  speedily  and  uncompromisingly,  but  for  all  time. 

The  main  point  at  issue  concerned  the  central  doc- 
trine of  the  old  chemistry — the  doctrine  of  Becher  and 
Stahl,  that  the  only  combustible  substance  in  nature  is 
a  kind  of  matter  called  phlogiston,  which  enters  into 
the  composition  of  other  bodies  in  varying  degree,  thus 
determining  their  inflammability.  This  theory  seems 
crude  enough  now,  since  we  know  that  phlogiston  was  a 
purely  fictitious  element,  yet  it  served  an  excellent  pur- 
pose when  it  was  propounded  and  it  held  its  place  as 
the  central  doctrine  of  chemical  philosophy  for  almost  a 
century. 

At  the  time  when  this  theory  was  put  forward,  it 
must  be  recalled,  the  old  Aristotelian  idea  that  the  four 
primal  elements  are  earth,  air,  fire,  and  water  still  held 
sway  as  the  working  foundation  of  all  chemical  philoso- 
phies. Air  and  water  were  accepted  as  simple  bodies. 
Only  a  few  acids  and  alkalies  were  known,  and  these 
but  imperfectly ;  and  the  existence  of  gases  as  we  now 

29 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

know  them,  other  than  air,  was  hardly  so  much  as  sus- 
pected.    All  the  known  facts  of  chemistry  seemed  then 


JOSEPH   PRIESTLY 


to  harmonize  with  the  phlogiston  hypothesis ;  and  so, 
later  on,  did  the  new  phenomena  which  were  discovered 

30 


SCIENCE  AT  THE  BEGINNING  OF  THE  CENTURY 

in  such  profusion  during  the  third  quarter  of  the  eigh- 
teenth century  —  the  epoch  of  pneumatic  chemistry. 
Hydrogen  gas,  discovered  by  Cavendish  in  1776,  and 
called  inflammable  air,  was  thought  by  some  chemists 
to  be  the  very  principle  of  phlogiston  itself.  Other 
"airs"  were  adjudged  " dephlogisticated  "  or  " phlogis- 
ticated."  in  proportion  as  they  supported  or  failed  to 
support  combustion.  The  familiar  fact  of  a  candle 
flame  going  out  when  kept  in  a  confined  space  of  or- 
dinary air  was  said  to  be  due  to  the  saturation  of  this 
air  with  phlogiston.  And  all  this  seemed  to  tally  beau- 
tifully with  the  prevailing  theory. 

But  presently  the  new  facts  began,  as  new  facts  al- 
ways will,  to  develop  an  iconoclastic  tendency.  The 
phlogiston  theory  had  dethroned  fire  from  its  primacy 
as  an  element  by  alleging  that  flame  is  due  to  a  union 
of  the  element  heat  with  the  element  phlogiston.  Now 
earths  were  decomposed,  air  and  water  were  shown  to 
be  compound  bodies,  and  at. last  the  existence  of  phlo- 
giston itself  was  to  be  called  in  question.  The  structure 
of  the  old  chemical  philosophy  had  been  completely  rid- 
dled ;  it  was  now  to  be  overthrown.  The  culminating 
observation  which  brought  matters  to  a  crisis  was  the 

•j  discovery  of  oxygen,  which  was  made  by  Priestley  in 
England  and  Scheele  in  Sweden,  working  independently, 
in  the  year  1774.  Priestley  called  the  new  element  "  de- 
phlogisticated air";  Scheele  called  it  "empyreal  air." 

But  neither  Priestley  nor  Scheele  realized  the  full  im- 
port of  this  discovery ;  nor,  for  that  matter,  did  any 
one  else  at  the  moment.  Very  soon,  however,  one  man 
at  least  had  an  inkling  of  it.  This  was  the  great  French 

\  chemist  Antoine  Laurent  Lavoisier.  It  has  sometimes 
been  claimed  that  he  himself  discovered  oxygen  inde- 

31 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

pendently  of  Priestley  and  Scbeele.  At  all  events,  he  at 
once  began  experimenting  with  it,  and  very  soon  it 
dawned  upon  him  that  this  remarkable  substance  might 
furnish  a  key  to  the  explanation  of  many  of  the  puzzles 
of  chemistry.  He  found  that  oxygen  is  consumed  or 
transformed  during  the  combustion  of  any  substance  in 
air.  He  reviewed  the  phenomena  of  combustion  in  the 
light  of  this  new  knowledge.  It  seemed  to  him  that 
the  new  element  explained  them  all  without  aid  of  the 
supposititious  element  phlogiston.  What  proof,  then, 
have  we  that  phlogiston  exists  ?  Very  soon  he  is  able 
to  answer  that  there  is  no  proof,  no  reason  to  believe 
that  it  exists.  Then  why  not  denounce  phlogiston  as  a 
myth,  and  discard  it  from  the  realm  of  chemistry  ? 

Precisely  this  is  what  Lavoisier  purposes  to  do.  He 
associates  with  him  three  other  famous  French  chemists, 
Berthollet,  Guy  ton  de  Morveau,  and  Fourcroy,  and  sets 
to  work  to  develop  a  complete  system  of  chemistry  based 
on  the  new  conception.  In  1788  the  work  is  completed 
and  given  to  the  world.  It  is  not  merely  an  epoch-mak- 
ing book;  it  is  revolutionary.  It  discards  phlogiston 
altogether,  alleging  that  the  elements  really  concerned 
in  combustion  are  oxygen  and  heat.  It  claims  that 
acids  are  compounds  of  oxygen  with  a  base,  instead  of 
mixtures  of  "  earth  "  and  water ;  that  metals  are  simple 
elements,  not  compounds  of  "  earth  "  and  "  phlogiston  " ; 
and  that  water  itself,  like  air,  is  a  compound  of  oxygen 
with  another  element. 

In  applying  these  ideas  the  new  system  proposes  an 
altogether  new  nomenclature  for  chemical  substances. 
Hitherto  the  terminology  of  the  science  has  been  a  mat- 
ter of  whim  and  caprice.  Such  names  as  "  liver  of  sul- 
phur," "  mercury  of  life,"  "  horned  moon,"  "  the  double 

32  . 


SCIENCE  AT  THE  BEGINNING  OF  THE  CENTURY 

secret,"  "the  salt  of  many  virtues,"  and  the  like, 
have  been  accepted  without  protest  by  the  chemical 
world.  With  such  a  terminology  continued  progress 
was  as  impossible  as  human  progress  without  speech. 
The  new  chemistry  of  Lavoisier  and  his  confreres,  fol- 
lowing the  model  set  by  zoology  half  a  century  earlier, 
designates  each  substance  by  a  name  instead  of  a  phrase, 
applies  these  names  according  to  fixed  rules,  and:  in 
short,  classifies  the  chemical  knowledge  of  the  time  and 
brings  it  into  a  system,  lacking  which  no  body  of  knowl- 
edge has  full  title  to  the  name  of  science. 

Though  Lavoisier  was  not  alone  in  developing  this 
revolutionary  scheme,  posterity  remembers  him  as  its 
originator.  His  dazzling  and  comprehensive  genius  ob- 
scured the  feebler  lights  of  his  confreres.  Perhaps,  too, 
his  tragic  fate  was  not  without  influence  in  augmenting 
his  posthumous  fame.  In  1794  he  fell  by  the  guillotine, 
guiltless  of  any  crime  but  patriotism — a  victim  of  the 
"  Reign  of  Terror."  "  The  Republic  has  no  need  of 
savants"  remarked  the  functionary  who  signed  the 
death-warrant  of  the  most  famous  chemist  of  the  cen- 
tury. 

The  leader  of  the  reform  movement  in  chemistry 
thus  died  at  the  hands  of  bigotry  and  fanaticism — 
rather,  let  us  say,  as  the  victim  of  a  national  frenzy — 
while  the  cause  he  championed  was  young,  yet  not  too 
soon  to  see  the  victory  as  good  as  won.  The  main  body 
of  French  chemists  had  accepted  the  new  doctrines  al- 
most from  the  first,  and  elsewhere  the  opposition  had 
been  of  that  fierce,  eager  type  which  soon  exhausts  itself 
in  the  effort.  At  Berlin  they  began  by  burning  Lovoi- 
sier  in  effigy,  but  they  ended  speedily  by  accepting  the 
new  theories.  In  England  the  fight  was  more  stubborn, 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

but  equally  decisive.  At  first  the  new  chemistry  was 
opposed  by  such  great  men  as  Black,  of  "  latent  heat " 
fame  ;  Rutherford,  the  discoverer  of  nitrogen ;  and  Cav- 
endish, the  inventor  of  the  pneumatic  trough  and  the 
discoverer  of  the  composition  of  water,  not  to  mention 
a  coterie  of  lesser  lights ;  but  one  by  one  the}7  wavered 
and  went  over  to  the  enemy.  Oddly  enough,  the 
doughtiest  and  most  uncompromising  of  all  the  cham- 
pions of  the  old  "  phlogistic  "  ideas  was  Dr.  Priestley, 
the  very  man  whose  discovery  of  oxygen  had  paved  the 
way  for  the  "antiphlogistic"  movement — a  fact  which 
gave  rise  to  Cuvier's  remark  that  Priestley  was  undoubt- 
edly one  of  the  fathers  of  modern  chemistry,  but  a 
father  who  never  wished  to  recognize  his  daughter. 

A  most  extraordinary  man  was  this  Dr.  Priestley. 
Davy  said  of  him,  a  generation  later,  that  no  other  per- 
son ever  discovered  so  many  new  and  curious  substances 
as  he  ;  yet  to  the  last  he  was  only  an  amateur  in  science, 
his  profession  being  the  ministry.  There  is  hardly  an- 
other case  in  history  of  a  man  not  a  specialist  in  science 
accomplishing  so  much  in  original  research  as  did  Joseph 
Priestley,  the  chemist,  physiologist,  electrician ;  the 
mathematician,  logician,  and  moralist ;  the  theolo- 
gian, mental  philosopher,  and  political  economist.  He 
took  all  knowledge  for  his  field ;  but  how  he  found  time 
for  his  numberless  researches  and  multifarious  writings, 
along  with  his  every-day  duties,  must  ever  remain  a 
mystery  to  ordinary  mortals. 

That  this  marvellously  receptive,  flexible  mind  should 
have  refused  acceptance  to  the  clearly  logical  doctrines 
of  the  new  chemistry  seems  equally  inexplicable.  But 
so  it  was.  To  the  very  last,  after  all  his  friends  had 
capitulated,  Priestley  kept  up  the  fight.  From  America, 

34 


SCIENCE   AT   THE   BEGINNING   OF  THE   CENTURY 

whither  he  had  gone  to  live  in  1794,  he  sent  out  the  last 
defy  to  the  enemy  in  1800,  in  a  brochure  entitled  "  The 
Doctrine  of  Phlogiston  Upheld,"  etc.  In  the  mind  of 
its  author  this  was  little  less  than  a  paean  of  victory ; 
but  all  the  world  besides  knew  that  it  was  the  swan- 
song  of .  the  doctrine  of  phlogiston.  Despite  the  defiance 
of  this  single  warrior  the  battle  was  really  lost  and  won, 
and  as  the  century  closed,  "antiphlogistic"  chemistry  had 
practical  possession  of  the  field. 


VI 

Several  causes  conspired  to  make  exploration  all  the 
fashion  during  the  closing  epoch  of  the  eighteenth  cen- 
tury. New  aid  to  the  navigator  had  been  furnished  by 
the  perfected  compass  and  quadrant,  and  by  the  invention 
of  the  chronometer;  medical  science  had  banished  scurvy, 
which  hitherto  had  been  a  perpetual  menace  to  the  voy- 
ager; and,  above  all,  the  restless  spirit  of  the  age  kn- 
pelled  the  venturesome  to  seek  novelty  in  fields  alto- 
gether new.  Some  started  for  the  pole,  others  tried  for 
a  northeast  or  northwest  passage  to  India,  yet  others 
sought  the  great  fictitious  antarctic  continent  told  of  by 
tradition.  All  these  of  course  failed  of  their  immediate 
purpose,  but  they  added  much  to  the  world's  store  of 
knowledge  and  its  fund  of  travellers'  tales. 

Among  all  these  tales  none  was  more  remarkable 
than  those  which  told  of  strange  living  creatures  found 
in  antipodal  lands.  And  here,  as  did  not  happen  in 
every  field,  the  narratives  were  often  substantiated  by 
the  exhibition  of  specimens  that  admitted  no  question. 
Many  a  company  of  explorers  returned  more  or  less 
laden  with  such  trophies  from  the  animal  and  vegetable 

35 


THE   STORY  OF   NINETEENTH-CENTURY  SCIENCE 

kingdoms,  to  the  mingled  astonishment,  delight,  and  be- 
wilderment of  the  closet  naturalists.  The  followers  of 
Linna3us  in  the  "golden  age  of  natural  history,"  a  few 
decades  before,  had  increased  the  number  of  known  spe- 
cies of  fishes  to  about  400,  of  birds  to  1000,  of  insects  to 
3000,  and  of  plants  to  10,000.  But  now  these  sudden 
accessions  from  ne\v  territories  doubled  the  figure  for 
plants,  tripled  it  for  fish  and  birds,  and  brought  the 
number  of  described  insects  above  20,000. 

Naturally  enough,  this  wealth  of  new  material  was 
sorely  puzzling  to  the  classifiers.  The  more  discerning 
began  to  see  that  the  artificial  system  of  Linna3us,  won- 
derful and  useful  as  it  had  been,  must  be  advanced  upon 
before  the  new  material  could  be  satisfactorily  disposed 
of.  The  way  to  a  more  natural  system,  based  on  less 
arbitrary  signs,  had  been  pointed  out  by  Jussieu  in 
botany,  but  the  zoologists  were  not  prepared  to  make 
headway  towards  such  a  system  until  they  should  gain  a 
wider  understanding  of  the  organisms  with  which  they 
had  to  deal  through  comprehensive  studies  of  anatomy. 
Such  studies  of  individual  forms  in  their  relations  to  the 
entire  scale  of  organic  beings  were  pursued  in  these  last 
decades  of  the  century,  but  though  two  or  three  most 
important  generalizations  were  achieved  (notably  Kaspar 
Wolff's  conception  of  the  cell  as  the  basis  of  organic  life, 
and  Goethe's  all-important  doctrine  of  metamorphosis 
of  parts),  yet,  as  a  whole,  the  work  of  the  anatomists  of 
the  period  was  germinative  rather  than  fruit-bearing. 
Bichat's  volumes,  telling  of  the  recognition  of  the  fun- 
damental tissues  of  the  body,  did  not  begin  to  appear 
till  the  last  year  of  the  century.  The  announcement  by 
Cuvier  of  the  doctrine  of  correlation  of  parts  bears  the 
same  date,  but  in  general  the  studies  of  this  great  nat- 

36 


LAVOISIER  IN   HIS  LABORATORY 


SCIENCE  AT  THE  BEGINNING  OF  THE  CENTURY 

uralist,  which  in  due  time  were  to  stamp  him  as  the 
successor  of  Linna3us,  were  as  yet  only  fairly  begun. 

In  the  field  of  physiology,  on  the  other  hand,  two 
most  important  works  were  fairly  consummated  in  this 
epoch — the  long-standing  problems  of  digestion  and 
respiration  were  solved,  almost  coincidently.  Two  very 
distinguished  physiologists  share  the  main  honors  of  dis- 
covery in  regard  to  the  function  of  digestion — the  Abbe 
Spallanzani,  of  the  University  of  Pa  via,  Italy,  and  John 
Hunter,  of  England.  Working  independently,  these  inves- 
tigators showed  at  about  the  same  time  that  digestion  is 
primarily  a  chemical  rather  than  a  mechanical  process. 
It  is  a  curious  commentary  on  the  crude  notions  of  me- 
chanics of  previous  generations  that  it  should  have  been 
necessary  to  prove  by  experiment  that  the  thin,  almost 
membranous  stomach  of  a  mammal  has  not  the  power  to 
pulverize,  by  mere  attrition,  the  foods  that  are  taken  into 
it.  However,  the  proof  was  now  for  the  first  time  forth- 
coming, and  the  question  of  the  general  character  of  the 
function  of  digestion  was  forever  set  at  rest. 

To  clear  up  the  mysteries  of  respiration  was  a  task  that 
fell  to  the  lot  of  chemistry.  The  solution  of  the  problem 
followed  almost  as  a  matter  of  course  upon  the  advances 
of  that  science  in  the  latter  part  of  the  century.  Hitherto 
no  one  since  Mayow,  of  the  previous  century,  whose  flash 
of  insight  had  been  strangely  overlooked  and  forgotten, 
had  even  vaguely  surmised  the  true  function  of  the  lungs. 
The  great  Boerhaave  had  supposed  that  respiration  is 
chiefly  important  as  an  aid  to  the  circulation  of  the 
blood ;  his  great  pupil,  Haller,  had  believed  to  the  day  of 
his  death  in  1777  that  the  main  purpose  of  the  function 
is  to  form  the  voice.  No  genius  could  hope  to  fathom 
the  mystery  of  the  lungs  so  long  as  air  was  supposed  to 

39 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

be  a  simple  element,  serving  a  mere  mechanical  purpose 
in  the  economy  of  the  earth. 

But  the  discovery  of  oxygen  gave  the  clew,  and  very 
soon  all  the  chemists  were  testing  the  air  that  came 
from  the  lungs — Dr.  Priestley,  as  usual,  being  in  the 
van.  His  initial  experiments  were  made  in  1777,  and 
from  the  outset  the  problem  was  as  good  as  solved. 
Other  experimenters  confirmed  his  results  in  all  their 
essentials — notably  Scheeleand  Lavoisier  and  Spallanzani 
and  Davy.  It  was  clearly  established  that  there  is  chem- 
ical action  in  the  contact  of  the  air  with  the  tissue  of  the 
lungs ;  that  some  of  the  oxygen  of  the  air  disappears, 
and  that  carbonic  acid  gas  is  added  to  the  inspired  air. 
It  was  shown,  too,  that  the  blood,  having  come  in  con- 
tact with  the  air,  is  changed  from  black  to  red  in  color. 
These  essentials  were  not  in  dispute  from  the  first.  But 
as  to  just  what  chemical  changes  caused  these  results 
was  the  subject  of  controversy.  Whether,  for  example, 
oxygen  is  actually  absorbed  into  the  blood,  or  whether 
it  merely  unites  with  carbon  given  off  from  the  blood, 
was  long  in  dispute. 

Each  of  the  main  disputants  was  biassed  by  his  own 
particular  views  as  to  the  moot  points  of  chemistry. 
Lavoisier,  for  example,  believed  oxj'gen  gas  to  be  com- 
posed of  a  metal  oxygen  combined  with  the  alleged  ele- 
ment heat;  Dr.  Priestley  thought  it  a  compound  of  pos- 
itive electricity  and  phlogiston  ;  and  Humphry  Davy, 
when  he  entered  the  lists,  a  little  later,  supposed  it  to  be 
a  compound  of  oxygen  and  light.  Such  mistaken  no- 
tions naturally  complicated  matters,  and  delayed  a  com- 
plete understanding  of  the  chemical  processes  of  respi- 
ration. It  was  some  time,  too,  before  the  idea  gained 
acceptance  that  the  most  important  chemical  changes 

40 


SCIENCE  AT  TIIE   BEGINNING  OF  THE  CENTURY 

do  not  occur  in  the  lungs  themselves,  but  in  the  ultimate 
tissues.  Indeed,  the  matter  was  not  clearly  settled  at 
the  close  of  the  century.  Nevertheless,  the  problem  of 
respiration  had  been  solved  in  its  essentials.  Moreover, 
the  vastly  important  fact  had  been  established  that  a 
process  essentially  identical  with  respiration  is  necessary 
to  the  existence  not  only  of  all  creatures  supplied  with 
lungs,  but  to  fishes,  insects,  and  even  vegetables  —  in 
short,  to  every  kind  of  living  organism. 


EDWARD  JENNER 

From  the  painting  by  Sir  Thomas  Lawrence 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

All  advances  in  science  have  a  bearing,  near  or  re- 
mote, on  the  welfare  of  our  race ;  but  it  remains  to 
credit  to  the  closing  decade  of  the  eighteenth  century  a 
discovery  which,  in  its  power  of  direct  and  immediate 
benefit  to  humanity,  surpasses  any  other  discovery  of 
this  or  any  previous  epoch.  Needless  to  say  I  refer  to 
Jenner's  discovery  of  the  method  of  preventing  small- 
pox by  inoculation  with  the  virus  of  cow-pox.  It  de- 
tracts nothing  from  the  merit  of  this  discovery  to  say 
that  the  preventive  power  of  accidental  inoculation  had 
long  been  rumored  among  the  peasantry  of  England. 
Such  vague,  unavailing  half-knowledge  is  often  the  fore- 
runner of  fruitful  discovery.  To  all  intents  and  purposes 
Jenner's  discovery  was  original  and  unique.  Neither, 
considered  as  a  perfected  method,  was  it  in  any  sense  an 
accident.  It  was  a  triumph  of  experimental  science; 
how  great  a  triumph  it  is  difficult  now  to  understand,  for 
we  of  to-day  can  only  vaguely  realize  what  a  ruthless  and 
ever-present  scourge  small-pox  had  been  to  all  previous 
generations  of  men  since  history  began.  Despite  all 
efforts  to  check  it  by  medication  and  by  direct  inocula- 
tion, it  swept  now  and  then  over  the  earth  as  an  all- 
devastating  pestilence,  and  year  by  year  it  claimed  one- 
tenth  of  all  the  beings  in  Christendom  by  death  as  its 
average  quota  of  victims.  "  From  small-pox  and  love 
but  few  remain  free,"  ran  the  old  saw.  A  pitted  face 
was  almost  as  much  a  matter  of  course  a  hundred  years 
ago  as  a  smooth  one  is  to-day. 

Little  wonder,  then,  that  the  world  gave  eager  ac- 
ceptance to  Jenner's  discovery.  The  first  vaccination 
was  made  in  1Y96.  Before  the  close  of  the  century  the 
method  was  practised  everywhere  in  Christendom.  No 
urging  was  needed  to  induce  the  majority  to  give  it 

42 


SCIENCE  AT  THE   BEGINNING  OF  THE  CENTURY 

trial;  passengers  on  a  burning  ship  do  not  hold  aloof 
from  the  life-boats.  Rich  and  poor,  high  and  low, 
sought  succor  in  vaccination,  and  blessed  the  name  of 
their  deliverer.  Of  all  the  great  names  that  were  be- 
fore the  world  in  the  closing  days  of  the  century, 
there  was  perhaps  no  other  one  at  once  so  widely 
known  and  so  uniformly  reverenced  as  that  of  the  Eng- 
lish physician  Edward  Jenner.  Surely  there  was  no 
other  one  that  should  be  recalled  with  greater  gratitude 
by  posterity. 


CHAPTER  II 
THE   CENTURY'S    PROGRESS   IN   ASTRONOMY 


THE  first  day  of  our  century  was  fittingly  signalized 
by  the  discovery  of  a  new  world.  On  the  evening  of 
January  1,  1801,  an  Italian  astronomer,  Piazzi,  observed 
an  apparent  star  of  about  the  eighth  magnitude  (hence, 
of  course,  quite  invisible  to  the  unaided  eye),  which  later 
on  was  seen  to  have  moved,  and  was  thus  shown  to  be 
vastly  nearer  the  earth  than  any  true  star.  He  at  first 
supposed,  as  Herschel  had  done  when  he  first  saw 
Uranus,  that  the  unfamiliar  body  was  a  comet;  but 
later  observation  proved  it  a  tiny  planet,  occupying  a 
position  in  space  between  Mars  and  Jupiter.  It  was 
christened  Ceres,  after  the  tutelary  goddess  of  Sicily. 

Though  unpremeditated,  this  discovery  was  not  un- 
expected, for  astronomers  had  long  surmised  the  exist- 
ence of  a  planet  in  the  wide  gap  between  Mars  and 
Jupiter.  Indeed,  they  were  even  preparing  to  make 
concerted  search  for  it,  despite  the  protests  of  philoso- 
phers, who  argued  that  the  planets  could  not  possibly 
exceed  the  magic  number  seven,  when  Piazzi  forestalled 
their  efforts.  But  a  surprise  came  with  the  sequel;  for 
the  very  next  year  Dr.  Gibers,  the  wonderful  physician- 
astronomer  of  Bremen,  while  following  up  the  course  of 

44 


FRIEDKICH  WILHELM  BESSEL 


OF    THK 

UNIVERSITT 


\ 


THE   CENTURY'S   PROGRESS   IN  ASTRONOMY 

Ceres,  happened  on  another  tiny  moving  star,  similarly 
}}  located,  which  soon  revealed  itself  as  planetary.  Thus 
two  planets  were  found  where  only  one  was  expected* 

The  existence  of  the  supernumerary  was  a  puzzle,  but 
Olbers  solved  it  for  the  moment  by  suggesting  that 
Ceres  and  Pallas,  as  he  called  his  captive,  might  be  frag- 
ments of  a  quondam  planet,  shattered  by  internal  ex- 
plosion, or  by  the  impact  of  a  comet.  Other  similar 
fragments,  he  ventured  to  predict,  would  be  found  when 
searched  for.  William  Herschel  sanctioned  this  theory, 
and  suggested  the  name  asteroids  for  the  tiny  planets. 
The  explosion  theory  was  supported  by  the  discovery  of 
another  asteroid,  by  Harding,  of  Lilienthal,  in  1804,  and 
it  seemed  clinched  when  Olbers  himself  found  a  fourth 
in  1807.  The  new-comers  were  named  Juno  and  Yesta. 
respectively. 

There  the  case  rested  till  1845,  when  a  Prussian 
amateur  astronomer  named  Hencke  found  another  aste- 
roid, after  long  searching,  and  opened  a  new  epoch  of 
discovery.  From  then  on  the  finding  of  asteroids  be- 
came a  commonplace.  Latterly,  with  the  aid  of  pho- 
tography, the  list  has  been  extended  to  above  four  hun- 
dred, and  as  yet  there  seems  no  dearth  in  the  supply, 
though  doubtless  all  the  larger  members  have  been  re- 
vealed. Even  these  are  but  a  few  hundreds  of  miles  in 
diameter,  while  the  smaller  ones  are  too  tiny  for  meas- 
urement. The  combined  bulk  of  these  minor  planets  is 
believed  to  be  but  a  fraction  of  that  of  the  earth. 

Olbers's  explosion  theory,  long  accepted  by  astrono- 
mers, has  been  proven  open  to  fatal  objections.  The 
minor  planets  are  now  believed  to  represent  a  ring  of 
cosmical  matter,  cast  off  from  the  solar  nebula  like  the 
rings  that  went  to  form  the  major  planets,  but  prevented 

47 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

from  becoming  aggregated  into  a  single  body  by  the 
perturbing  mass  of  Jupiter. 

As  we  have  seen,  the  discovery  of  the  first  asteroid 
confirmed  a  conjecture  ;  the  other  important  planetary 
discovery  of  our  century  fulfilled  a  prediction.  Nep- 
tune was  found  through  scientific  prophecy.  No  one 
suspected  the  existence  of  a  trans-Uranian  planet  till 
Uranus  itself,  by  hair-breadth  departures  from  its  pre- 
dicted orbit,  gave  out  the  secret.  No  one  saw  the  dis- 
turbing planet  till  the  pencil  of  the  mathematician,  with 
almost  occult  divination,  had  pointed  out  its  place  in 
the  heavens.  The  general  predication  of  a  trans- 
TJranian  planet  was  made  by  Bessel,  the  great  Konigs- 
berg  astronomer,  in  184-0;  the  analysis  that  revealed  its 
exact  location  was  undertaken,  half  a  decade  later,  by 
two  independent  workers — John  Couch  Adams,  just 
graduated  senior  wrangler  at  Cambridge,  England,  and 
U.  J.  J.  Leverrier,  the  leading  French  mathematician  of 
his  generation. 

Adams's  calculation  was   first   begun  and  first  com- 

O 

pleted.  But  it  had  one  radical  defect — it  was  the  work 
of  a  young  and  untried  man.  So  it  found  lodgment  in  a 
pigeon-hole  of  the  desk  of  England's  Astronomer  Eoyal, 
and  an  opportunity  was  lost  which  English  astronomers 
have  never  ceased  to  mourn.  Had  the  search  been 
made,  an  actual  planet  would  have  been  seen  shining 
there,  close  to  the  spot  where  the  pencil  of  the  mathe- 
matician had  placed  its  hypothetical  counterpart.  But 
the  search  was  not  made,  and  while  the  prophecy  of 
Adams  gathered  dust  in  that  regrettable  pigeon-hole, 
Leverrier's  calculation  was  coming  on,  his  tentative 
results  meeting  full  encouragement  from  Arago  and 
other  French  savants.  At  last  the  laborious  calculations 

48 


THE    CENTURY'S   PROGRESS   IN   ASTRONOMY 

proved  satisfactory,  and,  confident  of  the  result,  Leverrier 
sent  to  the  Berlin  observatory,  requesting  that  search  be 
made  for  the  disturber  of  Uranus  in  a  particular  spot  of 
the  heavens.  Dr.  Galle  received  the  request  September 
23, 1846.  That  very  night  he  turned  his  telescope  to  the 
indicated  region,  and  there,  within  a  single  degree  of 
the  suggested  spot,  he  sa\v  a  seeming  star,  invisible  to 
the  unaided  eye,  which  proved  to  be  the  long-sought 
planet,  henceforth  to  be  known  as  Neptune.  To  the 
average  mind,  which  finds  something  altogether  mysti- 
fying about  abstract  mathematics,  this  was  a  feat 
savoring  of  the  miraculousr- 

Stimulated  by  this  success,  Leverrier  calculated  an 
orbit  for  an  interior  planet  from  perturbations  of  Mer- 
cury, but  though  prematurely  christened  Yulcan,  this 
hypothetical  nurseling  of  the  sun  still  haunts  the  realm 
of  the  undiscovered,  along  with  certain  equally  hypo- 
thetical trans-Neptunian  planets  whose  existence  has 
been  suggested  by  "residual  perturbations''  of  Uranus, 
and  by  the  movements  of  comets.  No  other  veritable 
additions  to  the  sun's  planetary  family  have  been  made 
in  our  century,  beyond  the  finding  of  seven  small  moons, 
which  chiefly  attest  the  advance  in  telescopic  powers. 
Of  these,  the  tiny  attendants  of  our  Martian  neighbor, 
discovered  by  Professor  Hall  with  the  great  Washington 
refractor,  are  of  greatest  interest,  because  of  their  small 
size  and  extremely  rapid  flight.  One  of  them  is  poised 
only  6000  miles  from  Mars,  and  whirls  about  him  almost 
four  times  as  fast  as  he  revolves,  seeming  thus,  as  viewed 
by  the  Martian,  to  rise  in  the  west  and  set  in  the  east,  and 
making  the  month  only  one-fourth  as  long  as  the  day. 

The  discovery  of  the  inner  or  crape  ring  of  Saturn, 
made  simultaneously  in  1850  by  William  C.  Bond,  at 
D  49 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

the  Harvard  observatory,  in  America,  and  the  Rev. 
W.  R.  Dawes  in  England,  was  another  interesting  op- 
tical achievement ;  but  our  most  important  advances 
in  knowledge  of  Saturn's  unique  system  are  due  to  the 
mathematician.  Laplace,  like  his  predecessors,  supposed 
these  rings  to  be  solid,  and  explained  their  stability  as 
due  to  certain  irregularities  of  contour  which  Herschel 
had  pointed  out.  But  about  1851  Professor  Peirce  of 
Harvard  showed  the  untenability  of  this  conclusion, 
proving  that  were  the  rings  such  as  Laplace  thought 
them,  they  must  fall  of  their  own  weight.  Then  Pro- 
fessor J.  Clerk  Maxwell  of  Cambridge  took  the  matter 
in  hand,  and  his  analysis  reduced  the  puzzling  rings  to  a 
cloud  of  meteoric  particles — a  "  shower  of  brickbats  " — 
each  fragment  of  which  circulates  exactly  as  if  it  were 
an  independent  planet,  though  of  course  perturbed  and 
jostled  more  or  less  by  its  fellows.  Mutual  perturbations, 
and  the  disturbing  pulls  of  Saturn's  orthodox  satellites, 
as  investigated  by  Max-well,  explain  nearly  all  the  phe- 
nomena of  the  rings  in  a  manner  highly  satisfactory. 

But  perhaps  the  most  interesting  accomplishments  of 
mathematical  astronomy — from  a  mundane  stand-point, 
at  any  rate — are  those  that  refer  to  the  earth's  own 
satellite.  That  seemingly  staid  body  was  long  ago 
discovered  to  have  a  propensity  to  gain  a  little  on  the 
earth,  appearing  at  eclipses  an  infinitesimal  moment 
ahead  of  time.  Astronomers  were  sorely  puzzled  by 
this  act  of  insubordination  ;  but  at  last  Laplace  and 
Lagrange  explained  it  as  due  to  an  oscillatory  change  in 
the  earth's  orbit,  thus  fully  exonerating  the  moon,  and 
seeming  to  demonstrate  the  absolute  stability  and  per- 
manence of  our  planetary  system,  which  the  moon's 
misbehavior  had  appeared  to  threaten. 

50 


THE   CENTURY'S   PROGRESS   IN  ASTRONOMY 

This  highly  satisfactory  conclusion  was  an  orthodox 
belief  of  celestial  mechanics  until  1853,  when  Professor 
Adams  of  Neptunian  fame,  with  whom  complex  analyses 
were  a  pastime,  reviewed  Laplace's  calculation,  and  dis- 
covered an  error,  which,  when  corrected,  left  about  half 
the  moon's  acceleration  unaccounted  for.  This  was  a 
momentous  discrepancy,  which  at  first  no  one  could 
explain.  But  presently  Professor  Helmholtz,  the  great 
German  physicist,  suggested  that  a  key  might  be  found 
in  tidal  friction,  which,  acting  as  a  perpetual  brake  on 
the  earth's  rotation,  and  affecting  not  merely  the  waters 
but  the  entire  substance  of  our  planet,  must  in  the  long 
sweep  of  time  have  changed  its  rate  of  rotation.  Thus 
the  seeming  acceleration  of  the  moon  might  be  account- 
ed for  as  actual  retardation  of  the  earth's  rotation — a 
lengthening  of  the  day  instead  of  a  shortening  of  the 
month. 

Again  the  earth  was  shown  to  be  at  fault,  but  this 
time  the  moon  could  not  be  exonerated,  while  the  esti- 
mated stability  of  our  system,  instead  of  being  re-estab- 
lished, was  quite  upset.  For  the  tidal  retardation  is  not 
an  oscillatory  change  which  will  presently  correct  itself, 
like  the  orbital  wobble,  but  a  perpetual  change,  acting 
always  in  one  direction.  Unless  fully  counteracted  by 
some  opposing  reaction,  therefore  (as  it  seems  not  to  be), 
the  effect  must  be  cumulative,  the  ultimate  consequences 
disastrous.  The  exact  character  of  these  consequences 
was  first  estimated  by  Professor  G.  H.  Darwin,  in  1879. 
He  showed  that  tidal  friction  in  retarding  the  earth 
must  also  push  the  moon  out  from  the  parent  planet  on 
a  spiral  orbit.  Plainly,  then,  the  moon  must  formerly 
have  been  nearer  the  earth  than  at  present.  At  some 
very  remote  period  it  must  have  actually  touched  the 

51 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

earth ;  must,  in  other  words,  have  been  thrown  off  from 
the  then  plastic  mass  of  the  earth,  as  a  polyp  buds  out 
from  its  parent  polyp.  At  that  time  the  earth  was  spin- 
ning about  in  a  day  of  from  two  to  four  hours. 

Now  the  day  has  been  lengthened  to  twenty-four 
hours,  and  the  moon  has  been  thrust  out  to  a  distance 
of  a  quarter-million  miles;  but  the  end  is  not  yet.  The 
same  progress  of  events  must  continue,  till,  at  some  re- 
mote period  in  the  future,  the  day  has  come  to  equal 
the  month,  lunar  tidal  action  has  ceased,  and  one  face  of 
the  earth  looks  out  always  at  the  moon,  with  that  same 
fixed  stare  which  even  now  the  moon  has  been  brought 
to  assume  towards  her  parent  orb.  Should  we  choose  to 
take  even  greater  liberties  with  the  future,  it  may  be 
made  to  appear  (though  some  astronomers  dissent  from 
this  prediction)  that,  as  solar  tidal  action  still  continues, 
the  day  must  finally  exceed  the  month,  and  lengthen 
out  little  by  little  towards  coincidence  with  the  }7ear; 
and  that  the  moon  meantime  must  pause  in  its  outward 
flight,  and  come  swinging  back  on  a  descending  spiral, 
until  finally,  after  the  lapse  of  untold  aeons,  it  ploughs 
and  ricochets  along  the  surface  of  the  earth,  and  plunges 
to  catastrophic  destruction. 

But  even  though  imagination  pause  far  short  of  this 
direful  culmination,  it  still  is  clear  that  modern  calcula- 
tions, based  on  inexorable  tidal  friction,  suffice  to  revo- 
lutionize the  views  formerly  current  as  to  the  stability 
of  the  planetary  system.  The  eighteenth-century  math- 
ematician looked  upon  this  system  as  a  vast  celestial 
machine  which  had  been  in  existence  about  six  thousand 
years,  and  which  was  destined  to  run  on  forever.  The 
analyst  of  to-day  computes  both  the  past  and  the  future 
of  this  system  in  millions  instead  of  thousands  of  years, 


THE   CENTURY'S   PROGRESS   IN  ASTRONOMY 

yet  feels  well  assured  that  the  solar  system  offers  no 
contradiction  to  those  laws  of  growth  and  decay  which 
seem  everywhere  to  represent  the  immutable  order  of 
nature. 


ii 

Until  the  mathematician  ferreted  oafche  secret,  it 
surely  never  could  have  been  suspected  l^any  one  that 
the  earth's  serene  attendant, 

"That  orbed  maiden,  with  white  fire  laden, 
Whom  mortals  call  the  moon," 

could  be  plotting  injury  to  her  parent  orb.  But  there 
is  another  inhabitant  of  the  skies  whose  purposes  have 
not  been  similarly  free  from  popular  suspicion.  Needless 
to  say  I  refer  to  the  black  sheep  of  the  sidereal  family, 
'that  "  celestial  vagabond  "  the  comet. 

Time  out  of  mind  these  wanderers  have  been  sup- 
posed to  presage  war,  famine,  pestilence,  perhaps  the 
destruction  of  the  world.  And  little  wonder.  Here  is 
a  body  which  comes  flashing  out  of  boundless  space  into 
our  system,  shooting  out  a  pyrotechnic  tail  some  hun- 
dreds of  millions  of  miles  in  length  ;  whirling  perhaps 
through  the  very  atmosphere  of  the  sun  at  a  speed  of 
three  or  four  hundred  miles  a  second ;  then  darting  off 
on  a  hyperbolic  orbit  that  forbids  it  ever  to  return,  or 
an  elliptical  one  that  cannot  be  closed  for  hundreds  or 
thousands  of  years ;  the  tail  meantime  pointing  always 
away  from  the  sun,  and  fading  to  nothingness  as  the 
weird  voyager  recedes  into  the  special  void  whence  it 
came.  Not  many  times  need  the  advent  of  such  an  ap- 
parition coincide  with  the  outbreak  of  a  pestilence,  or 
the  death  of  a  Caesar,  to  stamp  the  race  of  comets  as  an 

53 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

ominous  clan  in  the  minds  of  all  snperstitious  genera- 
tions. 

It  is  true  a  hard  blow  was  struck  at  the  prestige  of 
these  alleged  supernatural  agents  when  Newton  proved 
that  the  great  comet  of  1680  obeyed  Kepler's  laws  in  its 
flight  about  the  sun ;  and  an  even  harder  one  when  the 
same  visitant  came  back  in  1758,  obedient  to  Halley's 
prediction,  after  its  three-quarters  of  a  century  of  voy- 
aging out  in  the  abyss  of  space.  Proved  thus  to  bow  to 
natural  law,  the  celestial  messenger  could  no  longer 
fully  sustain  its  role.  But  long-standing  notoriety  can- 
not be  lived  clown  in  a  day,  and  the  comet,  though 
proved  a  "natural"  object,  was  still  regarded  as  a  very 
menacing  one  for  another  hundred  years  or  so.  It  re- 
mained for  our  own  century  to  completely  unmask  the 
pretender,  and  show  how  egregiously  our  forebears  had 
been  deceived. 

The  unmasking  began  early  in  the  century,  when  Dr. 
Olbers,  then  the  highest  authority  on  the  subject,  ex- 
pressed the  opinion  that  the  spectacular  tail,  which  had 
all  along  been  the  comet's  chief  stock  in  trade  as  an 
earth  -  threatener,  is  in  reality  composed  of  the  most 
filmy  of  vapors,  repelled  from  the  cometary  body  by  the 
sun,  presumably  through  electrical  action,  with  a  veloc- 
ity comparable  to  that  of  light.  This  luminous  sug- 
gestion was  held  more  or  less  in  abeyance  for  half  a  cen- 
tury. Then  it  was  elaborated  by  Zollner,  and  particu- 
larly by  Bredichin,  of  the  Moscow  observatory,  into 
what  has  since  been  regarded  as  the  most  plausible  of 
cometary  theories.  It  is  held  that  comets  and  the  sun 
are  similarly  electrified,  and  hence  mutually  repulsive. 
Gravitation  vastly  outmatches  this  repulsion  in  the 
body  of  the  comet,  but  yields  to  it  in  the  case  of  gases, 

54 


HEINRICH   WILHELM  MATTHIAS   OLBERS 


OF    THIi 

UNIVERSITY 


THE   CENTURY'S   PROGRESS   IN  ASTRONOMY 

because  electrical  force  varies  with  the  surface,  while 
gravitation  varies  only  with  the  mass.  From  study  of 
atomic  weights,  and  estimates  of  the  velocity  of  thrust 
of  cometary  tails,  Bredichin  concluded  that  the  chief 
components  of  the  various  kinds  of  tails  are  hydrogen, 
hydrocarbons,  and  the  vapor  of  iron ;  and  spectroscopic 
analysis  goes  far  towards  sustaining  these  assumptions. 

But,  theories  aside,  the  unsubstantialness  of  the  com- 
et's tail  has  been  put  to  a  conclusive  test.  Twice  during 
our  century  the  earth  has  actually  plunged  directly 
through  one  of  these  threatening  appendages,  in  1819, 
and  again  in  1861,  once  being  immersed  to  a  depth  of 
some  300,000  miles  in  its  substance.  Yet  nothing  dread- 
ful happened  to  us.  There  was  a  peculiar  glow  in  the 
atmosphere,  so  the  more  imaginative  observers  thought, 
and  that  was  all.  After  such  fiascoes,  the  cometary 
train  could  never  again  pose  as  a  world-destroyer. 

But  the  full  measure  of  the  comet's  humiliation  is,  not 
yet  told.  The  pyrotechnic  tail,  composed  as  it  is  of  por- 
tions of  the  comet's  actual  substance,  is  tribute  paid  the 
sun,  and  can  never  be  recovered.  Should  the  obeisance  to 
the  sun  be  many  times  repeated,  the  train-forming  mate- 
rial will  be  exhausted,  and  the  comet's  chiefest  glory  will 
have  departed.  Such  a  fate  has  actually  befallen  a  mul- 
titude of  comets,  which  Jupiter  and  the  other  outlying 
planets  have  dragged  into  our  system,  and  helped  the 
sun  to  hold  captive  here.  Many  of  these  tailless  comets 
were  known  to  the  eighteenth-century  astronomers,  but 
no  one  at  that  time  suspected  the  true  meaning  of  their 
condition.  It  was  not  even  known  how  closely  some  of 
them  are  enchained,  until  the  German  astronomer  Encke, 
in  1822,  showed  that  one  which  he  had  rediscovered,  and 
which  has  since  borne  his  name,  was  moving  in  an  orbit 

57 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

so  contracted  that  it  must  complete  its  circuit  in  about 
three  and  a  half  years.  Shortly  afterwards  another 
comet,  revolving  in  a  period  of  about  six  years,  was  dis- 
covered by  Biela,  and  given  his  name.  Only  two  more 
of  these  short-period  comets  were  discovered  during  our 
first  half -century,  but  latterly  they  have  been  shown  to 
be  a  numerous  family.  Nearly  twenty  are  known  which 
the  giant  Jupiter  holds  so  close  that  the  utmost  reach  of 
their  elliptical  tether  does  not  let  them  go  beyond  the 
orbit  of  Saturn.  These  aforetime  wanderers  have  adapt- 
ed themselves  wonderfully  to  planetary  customs,  for  all 
of  them  revolve  in  the  same  direction  with  the  planets, 
and  in  planes  not  wide  of  the  ecliptic. 

Checked  in  their  proud  hyperbolic  sweep,  made  cap- 
tive in  a  planetary  net,  deprived  of  their  trains,  these 
quondam  free  lances  of  the  heavens  are  now  mere 
shadows  of  their  former  selves.  Considered  as  to  mere 
bulk,  they  are  very  substantial  shadows,  their  extent  be- 
ing measured  in  hundreds  of  thousands  of  miles  ;  but 
their  actual  mass  is  so  slight  that  they  are  quite  at  the 
mercy  of  the  gravitation  pulls  of  their  captors.  And 
worse  is  in  store  for  them.  So  persistently  do  sun  and 
planets  tug  at  them  that  they  are  doomed  presently  to 
be  torn  into  shreds. 

Such  a  fate  has  already  overtaken  one  of  them,  under 
the  very  eyes  of  the  astronomers,  within  the  relatively 
short  period  during  which  these  ill-fated  comets  have 
been  observed.  In  1832  Biela's  comet  passed  quite  near 
the  earth,  as  astronomers  measure  distance,  and  in  doing 
so  created  a  panic  on  our  planet.  It  did  no  greater  harm 
than  that,  of  course,  and  passed  on  its  way  as  usual. 
The  very  next  time  it  came  within  telescopic  hail  it  was 
seen  to  have  broken  into  two  fragments.  Six  years  later 

58 


THE   CENTURY'S   PROGRESS   IN  ASTRONOMY 

these  fragments  were  separated  by  many  millions  of 
miles ;  and  in  1852,  when  the  comet  was  due  again,  as- 
tronomers  looked  for  it  in  vain.  It  had  been  completely 
shattered. 

What  had  become  of  the  fragments  ?  At  that  time 
no  one  positively  knew.  But  the  question  was  to  be 
answered  presently.  It  chanced  that  just  at  this  period 
astronomers  were  paying  much  attention  to  a  class  of 
bodies  which  they  had  hitherto  somewhat  neglected,  the 
familiar  shooting-stars  or  meteors.  The  studies  of  Pro- 
fessor Newton  of  Yale  and  Professor  Adams  of  Cam- 
bridge with  particular  reference  to  the  great  meteor- 
shower  of  November,  1866,  which  Professor  Newton 
had  predicted,  and  shown  to  be  recurrent  at  intervals  of 
thirty-three  years,  showed  that  meteors  are  not  mere 
sporadic  swarms  of  matter  flying  at  random,  but  exist 
in  isolated  swarms,  and  sweep  about  the  sun  in  regular 
elliptical  orbits. 

Presently  it  was  shown  by  the  Italian  astronomer 
Schiaparelli  that  one  of  these  meteor  swarms  moves 
in  the  orbit  of  a  previously  observed  comet,  and  other 
coincidences  of  the  kind  were  soon  forthcoming.  The 
conviction  grew  that  meteor  swarms  are  really  the 
debris  of  comets  ;  and  this  conviction  became  a  prac- 
tical certainty  when,  in  November,  1872,  the  earth 
crossed  the  orbit  of  the  ill-starred  Biela,  and  a  shower 
of  meteors  came  whizzing  into  our  atmosphere  in  lieu  of 
the  lost  comet. 

And  so  at  last  the  full  secret  was  out.  The  awe-inspir- 
ing comet,  instead  of  being  the  planetary  body  it  had  all 
along  been  regarded,  is  really  nothing  more  nor  less 
than  a  great  aggregation  of  meteoric  particles,  which 
have  become  clustered  together  out  in  space  somewhere, 

59 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

and  which  by  jostling  one  another  or  through  electrical 
action  become  luminous.  So  widely  are  the  individual 
particles  separated  that  the  cometary  body  as  a  whole 
has  been  estimated  to  be  thousands  of  times  less  dense 
than  the  earth's  atmosphere  at  sea-level.  Hence  the 
ease  with  which  the  comet  may  be  dismembered  and  its 
particles  strung  out  into  streaming  swarms. 

So  thickly  is  the  space  we  traverse  strewn  with  this 
cometary  dust  that  the  earth  sweeps  up,  according  to 
Professor  Newcomb's  estimate,  a  million  tons  of  it  each 
day.  Each  individual  particle,  perhaps  no  larger  than 
a  millet  seed,  becomes  a  shooting-star  or  meteor  as  it 
burns  to  vapor  in  the  earth's  upper  atmosphere.  And 
if  one  tiny  planet  sweeps  up  such  masses  of  this  cosmic 
matter,  the  amount  of  it  in  the  entire  stretch  of  our  sys- 
tem must  be  beyond  all  estimate.  What  a  story  it  tells 
of  the  myriads  of  cometary  victims  that  have  fallen  prey 
to  the  sun  since  first  he  stretched  his  planetary  net  across 
the  heavens. 

in 

When  Biela's  comet  gave  the  inhabitants  of  the  earth 
such  a  fright  in  1832,  it  really  did  not  come  within 
fifty  millions  of  miles  of  us.  Even  the  great  comet 
through  whose  filmy  tail  the  earth  passed  in  1861  was 
itself  fourteen  millions  of  miles  away.  The  ordi- 
nary mind,  schooled  to  measure  space  by  the  tiny 
stretches  of  a  pygmy  planet,  cannot  grasp  the  import  of 
such  distances ;  yet  these  are  mere  units  of  measure 
compared  with  the  vast  stretches  of  sidereal  space. 
Were  the  comet  which  hurtles  past  us  at  a  speed  of, 
say,  a  hundred  miles  a  second  to  continue  its  mad  flight 
unchecked  straight  out  into  the  void  of  space,  it  must  fly 

60 


SIR  JOHN   HERSCHEL 

From  the  painting  by  H.  W.  Pickersgill,  R.  A.,  in  St.  John's  College,  Cambridge 


OF    THK 

UNIVERSITY 


THE  CENTURY'S   PROGRESS   IN  ASTRONOMY 

on  its  frigid  way  eight  thousand  years  before  it  could 
reach  the  very  nearest  of  our  neighbor  stars ;  and  even 
then  it  would  have  penetrated  but  a  mere  arrays-length 
into  the  vistas  where  lie  the  dozen  or  so  of  sidereal  resi- 
dents that  are  next  beyond.  Even  to  the  trained  mind 
such  distances  are  only  vaguely  imaginable.  Yet  the 
astronomer  of  our  century  has  reached  out  across  this 
unthinkable  void  and  brought  back  many  a  secret 
which  our  predecessors  thought  forever  beyond  human 
grasp. 

A  tentative  assault  upon  this  stronghold  of  the  stars 
was  being  made  by  Herschel  at  the  beginning  of  the 
century.  In  1802  that  greatest  of  observing  astrono- 
mers announced  to  the  Royal  Society  his  discovery  that 
certain  double  stars  had  changed  their  relative  positions 
towards  one  another  since  he  first  carefully  charted 
them  twenty  years  before.  Hitherto  it  had  been  sup- 
posed that  double  stars  were  mere  optical  effects.  Now 
it  became  clear  that  some  of  them,  at  any  rate,  are  true 
"  binary  systems,"  linked  together  presumably  by  gravi- 
tation, and  revolving  about  one  another.  Halley  had 
shown,  three-quarters  of  a  century  before,  that  the  stars 
have  an  actual  or  "proper"  motion  in  space;  Herschel 
himself  had  proved  that  the  sun  shares  this  motion  with 
the  other  stars.  Here  was  another  shift  of  place,  hith- 
erto quite  unsuspected,  to  be  reckoned  with  by  the  as- 
tronomer in  fathoming  sidereal  secrets. 

When  John  Herschel,  the  only  son  and  the  worthy 
successor  of  the  great  astronomer,  began  star-gazing  in 
earnest,  after  graduating  senior  wrangler  at  Cambridge, 
and  making  two  or  three  tentative  professional  starts  in. 
other  directions  to  which  his  versatile  genius  impelled 
him,  his  first  extended  work  was  the  observation  of  his 

68 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

father's  double  stars.  His  studies,  in  which  at  first  he  had 
the  collaboration  of  Mr.  James  South,  brought  to  light 
scores  of  hitherto  unrecognized  pairs,  and  gave  fresh 
data  for  the  calculation  of  the  orbits  of  those  longer 
known.  So  also  did  the  independent  researches  of  F. 
G.  W.  Struve,  the  enthusiastic  observer  of  the  famous 
Russian  observatory  at  the  university  of  Dorpat,  and 
subsequently  at  Pulkowa.  Utilizing  data  gathered  by 
these  observers,  M.  Savary  of  Paris  showed  in  1827  that 
the  observed  elliptical  orbits  of  the  double  stars  are  ex- 
plicable by  the  ordinary  laws  of  gravitation,  thus  con- 
firming the  assumption  that  Newton's  laws  apply  to 
these  sidereal  bodies.  Henceforth  there  could  be  no 
reason  to  doubt  that  the  same  force  which  holds  terres- 
trial objects  on  our  globe  pulls  at  each  and  every  par- 
ticle of  matter  throughout  the  visible  universe. 

The  pioneer  explorers  of  the  double  stars  early  found 
that  the  systems  into  which  the  stars  are  linked  are  by 
no  means  confined  to  single  pairs.  Often  three  or  four 
stars  are  found  thus  closely  connected  into  gravitation 
systems;  indeed,  there  are  all  gradations  between  bi- 
nary systems  and  great  clusters  containing  hundreds  or 
even  thousands  of  members.  It  is  known,  for  example, 
that  the  familiar  cluster  of  the  Pleiades  is  not  merely 
an  optical  grouping,  as  was  formerly  supposed,  but  an 
actual  federation  of  associated  stars,  some  2500  in  num- 
ber, only  a  few  of  which  are  visible  to  the  unaided  eye. 
And  the  more  carefully  the  motions  ot  the  stars  are 
studied,  the  more  evident  it  becomes  that  widely  sepa- 
rated stars  are  linked  together  into  infinitely  complex 
systems,  as  yet  but  little  understood.  At  the  same  time 
all  instrumental  advances  tend  to  resolve  more  and  more 
seemingly  single  stars  into  close  pairs  and  minor  clus- 

64 


I 
THE   CENTURY'S   PROGRESS   IN   ASTRONOMY 

ters.  The  two  Herschels  between  them  discovered 
some  thousands  of  these  close  multiple  systems;  Struve 
and  others  increased  the  list  to  above  ten  thousand ; 
and  Mr.  S.  W.  Burnham,  of  late  years  the  most  enthusi- 
astic and  successful  of  double -star  pursuers,  added  a 
thousand  new  discoveries  while  he  was  still  an  amateur 
in  astronomy,  and  by  profession  the  stenographer  of  a 
Chicago  court.  Clearly  the  actual  number  of  multiple 
stars  is  beyond  all  present  estimate. 

The  elder  Herschel's  early  studies  of  double  stars 
were  undertaken  in  the  hope  that  these  objects  might 
aid  him  in  ascertaining  the  actual  distance  of  a  star, 
through  measurement  of  its  annual  parallax ;  that  is  to 
say,  of  the  angle  which  the  diameter  of  the  earth's  orbit 
would  subtend  as  seen  from  the  star.  The  expectation 
was  not  fulfilled.  The  apparent  shift  of  position  of  a 
star  as  viewed  from  opposite  sides  of  the  earth's  orbit, 
from  which  the  parallax  might  be  estimated,  is  so  ex- 
tremely minute  that  it  proved  utterly  inappreciable, 
even  to  the  almost  preternaturally  acute  vision  of  Her- 
schel,  with  the  aid  of  any  instrumental  means  then  at 
command.  So  the  problem  of  star  distance  allured  and 
eluded  him  to  the  end,  and  he  died  in  1822  without  see- 
ing it  even  in  prospect  of  solution.  His  estimate  of  the 
minimum  distance  of  the  nearest  star,  based  though  it 
was  on  the  fallacious  test  of  apparent  brilliancy,  was  a 
singularly  sagacious  one,  but  it  was  at  best  a  scientific 
guess,  not  a  scientific  measurement. 

Just  about  this  time,  however,  a  great  optician  came 
to  the  aid  of  the  astronomers.  Joseph  Fraunhofer  per- 
fected the  refracting  telescope,  as  Herschel  had  perfected 
the  reflector,  and  invented  a  wonderfully  accurate  "  he- 
liometer,"  or  sun-measurer.  With  the  aid  of  these  in- 

E  65 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

struments  the  old  and  almost  infinitely  difficult  problem 
of  star  distance  was  solved.     In  1838  Bessel  announced 

|  from  the  Konigsberg  observatory  that  he  had  succeeded, 
after  months  of  effort,  in  detecting  and  measuring  the 

'  parallax  of  a  star.  Similar  claims  had  been  made  often 
enough  before?  always  to  prove  fallacious  when  put  to 
further  test;  but  this  time  the  announcement  carried 
the  authority  of  one  of  the  greatest  astronomers  of  the 
age,  and  scepticism  was  silenced. 

Xor  did  Bessel's  achievement  long  await  corrobora- 
tion.  Indeed,  as  so  often  happens  in  fields  of  discov- 
ery, two  other  workers  had  almost  simultaneously 
solved  the  same  problem — Struve  at  Pulkowa,  where 
the  great  Russian  observatory,  which  so  long  held  the 
palm  over  all  others,  had  now  been  established ;  and 
Thomas  Henderson,  then  working  at  the  Cape  of  Good 
Hope,  but  afterwards  the  Astronomer  Koyal  of  Scotland. 
Henderson's  observations  had  actual  precedence  in  point 
of  time,  but  Bessel's  measurements  were  so  much  more 
numerous  and  authoritative  that  he  has  been  uniformly 
considered  as  deserving  the  chief  credit  of  the  discovery, 
which  priority  of  publication  secured  him. 

By  an  odd  chance,  the  star  on  which  Henderson's  ob- 
servations were  made,  and  consequently  the  first  star  the 
parallax  of  which  was  ever  measured,  is  our  nearest 
neighbor  in  sidereal  space,  being,  indeed,  some  ten  bill- 
ions of  miles  nearer  than  the  one  next  beyond.  Yet 
even  this  nearest  star  is  more  than  200,000  times  as  re- 
mote from  us  as  the  sun.  The  sun's  light  flashes  to  the 
earth  in  eight  minutes,  and  to  Neptune  in  about  three 
and  a  half  hours,  but  it  requires  three  and  a  half  years 

\  to  signal  Alpha  Centauri.  And  as  for  the  great  major- 
ity of  the  stars,  had  they  been  blotted  out  of  existence 


THE  GREAT  REFRACTOR  OP  THE  NATIONAL  OBSERVATORY 
AT  WASHINGTON 


OF    THK 

UNIVERSITY 


THE  CENTURY'S   PROGRESS   IN   ASTRONOMY 

before  the  Christian  era,  we  of  to-day  should  still  re- 
ceive their  light  and  seem  to  see  them  just  as  we  do. 
When  we  look  up  to  the  sky,  we  study  ancient  history ; 
we  do  not  see  the  stars  as  they  are,  but  as  they  were 
years,  centuries,  even  millennia  ago. 

The  information  derived  from  the  parallax  of  a  star 
by  no  means  halts  with  the  disclosure  of  the  distance  of 
that  body.  Distance  known,  the  proper  motion  of  the 
star,  hitherto  only  to  be  reckoned  as  so  many  seconds  of 
arc,  may  readily  be  translated  into  actual  speed  of  prog- 
ress ;  relative  brightness. becomes  absolute  lustre,  as  com- 
pared with  the  sun  *  and  in  the  case  of  the  double  stars 
the  absolute  mass  of  the  components  may  be  computed 
from  the  laws  of  gravitation.  It  is  found  that  stars 
differ  enormously  among  themselves  in  all  these  regards. 
As  to  speed,  some,  like  our  sun,  barely  creep  through 
space— compassing  ten  or  twenty  miles  a  second,  it  is 
true,  yet  even  at  that  rate  only  passing  through  the 
equivalent  of  their  own  diameter  in  a  day.  At  the 
other  extreme,  among  measured  stars,  is  one  that 
moves  two  hundred  miles  a  second ;  yet  even  this  "fly- 
ing star,"  as  seen  from  the  earth,  seems  to  change  its 
place  by  only  about  three  and  a  half  lunar  diameters 
in  a  thousand  years.  In  brightness,  some  stars  yield  to 
the  sun,  while  others  surpass  him  as  the  arc-light  sur- 
passes a  candle.  Arcturus,  the  brightest  measured  star, 
shines  like  two  hundred  suns ;  and  even  this  giant  orb 
is  dim  beside  those  other  stars  which  are  so  distant  that 
their  parallax  cannot  be  measured,  yet  which  greet  our 
eyes  at  first  magnitude.  As  to  actual  bulk,  of  which 
apparent  lustre  furnishes  no  adequate  test,  some  stars 
are  smaller  than  the  sun,  while  others  exceed  him  hun- 
dreds or  perhaps  thousands  of  times.  Yet  one  and  all, 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

so  distant  are  they,  remain  mere  diskless  points  of  light 
before  the  utmost  powers  of  the  modern  telescope. 

All  this  seems  wonderful  enough,  but  even  greater 
things  were  in  store.  In  1859  the  spectroscope  came 
i  upon  the  scene,  perfected  by  Kirchhoff  and  Bunsen, 
f  along  lines  pointed  out  by  Fraunhofer  almost  half  a 
century  before.  That  marvellous  instrument,  by  reveal- 
ing the  telltale  lines  sprinkled  across  a  prismatic  spec- 
trum, discloses  the  chemical  nature  and  physical  condi- 
tion of  any  substance  whose  light  is  submitted  to  it, 
telling  its  story  equally  well,  provided  the  light  be 
strong  enough,  whether  the  luminous  substance  be  near 
or  far — in  the  same  room  or  at  the  confines  of  space. 
Clearly  such  an  instrument  must  prove  a  veritable  magic 
wand  in  the  hands  of  the  astronomer. 

Very  soon  eager  astronomers  all  over  the  world  were 
putting  the  spectroscope  to  the  test.  Kirchhoff  himself 
led  the  way,  and  Donati  and  Father  Secchi  in  Italy, 
Huggins  and  Miller  in  England,  and  Rutherfurd  in 
|f  America,  were  the  chief  of  his  immediate  followers. 
The  results  exceeded  the  dreams  of  the  most  visionary. 
At  the  very  outset,  in  1860,  it  was  shown  that  such 
common  terrestrial  substances  as  sodium,  iron,  calcium, 
magnesium,  nickel,  barium,  copper,  and  zinc  exist  in  the 
form  of  glowing  vapors  in  the  sun,  and  very  soon  the 
stars  gave  up  a  corresponding  secret.  Since  then  the 
work  of  solar  and  sidereal  analysis  has  gone  on  steadily 
in  the  hands  of  a  multitude  of  workers  (prominent 
among  whom,  in  this  country,  are  Professor  Young  of 
Princeton,  Professor  Langley  of  Washington,  and  Pro- 
fessor Pickering  of  Harvard),  and  more  than  half  the 
known  terrestrial  elements  have  been  definitely  located 
in  the  sun,  while  fresh  discoveries  are  in  prospect. 

70 


THE  CENTURY'S   PROGRESS   IN   ASTRONOMY 

It  is  true  the  sun  also  contains  some  seeming  elements 
that  are  unknown  on  the  earth,  but  this  is  no  matter  for 
surprise.  The  modern  chemist  makes  no  claim  for  his 


A   TYPICAL   STAR   CLUSTER—  CENTAURI 

elements  except  that  they  have  thus  far  resisted  all 
human  efforts  to  dissociate  them ;  it  would  be  nothing 
strange  if  some  of  them,  when  subjected  to  the  crucible 

71 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

of  the  sun,  which  is  seen  to  vaporize  iron,  nickel,  silicon, 
should  fail  to  withstand  the  test.  But  again,  chemistry 
has  by  no  means  exhausted  the  resources  of  the  earth's 
supply  of  raw  material,  and  the  substance  which  sends 
its  message  from  a  star  may  exist  undiscovered  in  the 
dust  we  tread  or  in  the  air  we  breathe.  Only  last  year 
two  new  terrestrial  elements  were  discovered  ;  but  one 
of  these  had  for  years  been  known  to  the  astronomer  as 
a  solar  and  suspected  as  a  stellar  element,  and  named 
helium  because  of  its  abundance  in  tho  sun.  The  spec- 
troscope had  reached  out  millions  of  miles  into  space 
and  brought  back  this  new  element:  and  it  took  the 
chemist  a  score  of  years  to  discover  that  he  had  all 
along  had  samples  of  the  same  substance  unrecognized 
in  his  sublunary  laboratory.  There  is  hardly  a  more 
picturesque  fact  than  that  in  the  entire  history  of 
science. 

But  the  identity  in  substance  of  earth  and  sun  and 
stars  was  not  more  clearly  shown  than  the  diversity  of 
their  existing  physical  conditions.  It  was  seen  that  sun 
and  stars,  far  from  being  the  cool,  earthlike,  habitable 
bodies  that  Herschel  thought  them  (surrounded  by 
glowing  clouds,  and  protected  from  undue  heat  by  other 
clouds),  are  in  truth  seething  caldrons  of  fiery  liquid,  or 
gas  made  viscid  by  condensation,  with  lurid  envelopes 
of  belching  flames.  It  was  soon  made  clear,  also,  par- 
ticularly by  the  studies  of  Kutherfurd  and  of  Secchi, 
that  stars  differ  among  themselves  in  exact  constitution 
or  condition.  There  are  white  or  Sirian  stars,  whose 
spectrum  revels  in  the  lines  of  hydrogen ;  yellow  or 
solar  stars  (our  sun  being  the  type),  showing  various 
metallic  vapors ;  and  sundry  red  stars,  with  banded 
spectra  indicative  of  carbon  compounds ;  besides,  the 

72 


THE   CENTURY'S   PROGRESS   IN  ASTRONOMY 

purely  gaseous  stars  of  more  recent  discovery,  which 
Professor  Pickering  had  specially  studied.  Zollner's 
famous  interpretation  of  these  diversities,  as  indicative 


SPECTRA  OF  STARS  IN  CARINA 

of  varying  stages  of  cooling,  has  been  called  in  question 
as  to  the  exact  sequence  it  postulates,  but  the  general 
proposition  that  stars  exist  under  widely  varying  condi- 
tions of  temperature  is  hardly  in  dispute. 

73 


THE   STORY   OF  NINETEENTH-CENTURY  SCIENCE 

The  assumption  that  different  star  types  mark  vary- 
ing stages  of  cooling  has  the  further  support  of  modern 
physics,  which  has  been  unable  to  demonstrate  any  way 
in  which  the  sun's  radiated  energy  may  be  restored,  or 
otherwise  made  perpetual,  since  meteoric  impact  has 
been  shown  to  be — under  existing  conditions  at  any 
rate — inadequate.  In  accordance  with  the  theory  of 
Helmholtz,  the  chief  supply  of  solar  energy  is  held  to 
be  contraction  of  the  solar  mass  itself,  and  plainly  this 
must  have  its  limits.  Therefore,  unless  some  means  as 
yet  unrecognized  is  restoring  the  lost  energy  to  the 
stellar  bodies,  each  of  them  must  gradually  lose  its  lus- 
tre, and  come  to  a  condition  of  solidification,  seeming 
sterility,  and  frigid  darkness.  In  the  case  of  our  own 
particular  star,  according  to  the  estimate  of  Lord  Kel- 
vin, such  a  culmination  appears  likely  to  occur  within  a 
period  of  five  or  six  million  years. 

But  by  far  the  strongest  support  of  such  a  forecast  as 
this  is  furnished  by  those  stellar  bodies  which  even  now 
appear  to  have  cooled  to  the  final  stage  of  star  develop- 
ment and  ceased  to  shine.  Of  this  class  examples  in 
miniature  are  furnished  by  the  earth  and  the  smaller  of 
its  companion  planets.  But  there  are  larger  bodies  of 
the  same  type  out  in  stellar  space — veritable  "dark 
stars  " — invisible,  of  course,  yet  nowadays  clearly  recog- 
nized. 

The  opening  up  of  this  "  astronomy  of  the  invisible  " 
is  another  of  the  great  achievements  of  our  century,  and 
again  it  is  Bessel  to  whom  the  honor  of  discovery  is  due. 
"While  testing  his  stars  for  parallax,  that  astute  observer 
was  led  to  infer,  from  certain  unexplained  aberrations  of 
motion,  that  various  stars,  Sirius  himself  among  the 
number,  are  accompanied  by  invisible  companions,  and 

74 


THE  CENTURY'S   PROGRESS   IN   ASTRONOMY 

in  1840  he  definitely  predicated  the  existence  of  such 
"dark  stars."  The  correctness  of  the  inference  was 
shown  twenty  }Tears  later,  when  Alvan  Clark,  Jun.,  the 
American  optician,  while  testing  a  new  lens,  discovered 


STAR   SPECTRA 


the  companion  of  Sirius,  which  proved  thus  to  be  faintly 
luminous.  Since  then  the  existence  of  other  and  quite 
invisible  star  companions  has  been  proved  incontestably, 

75 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

not  merely  by  renewed  telescopic  observations,  but  by 
the  curious  testimony  of  the  ubiquitous  spectroscope. 

One  of  the  most  surprising  accomplishments  of  that 
instrument  is  the  power  to  record  the  flight  of  a  luminous 
object  directly  in  the  line  of  vision.  If  the  luminous 
body  approaches  swiftly,  its  Fraunhofer  lines  are  shifted 
from  their  normal  position  towards  the  violet  end  of  the 
spectrum;  if  it  recedes,  the  lines  shift  in  the  opposite 
direction.  The  actual  motion  of  stars  whose  distance  is 
unknown  may  be  measured  in  this  way.  But  in  certain 
cases  the  light  lines  are  seen  to  oscillate  on  the  spectrum 
at  regular  intervals.  Obviously  the  star  sending  such 
light  is  alternately  approaching  and  receding,  and  the 
inference  that  it  is  revolving  about  a  companion  is  una- 
voidable. From  this  extraordinary  test  the  orbital  dis- 
tance, relative  mass,  and  actual  speed  of  revolution  of 
the  absolutely  invisible  body  may  be  determined.  Thus 
the  spectroscope,  which  deals  only  with  light,  makes 
paradoxical  excursions  into  the  realm  of  the  invisible. 
What  secrets  may  the  stars  hope  to  conceal  when  ques- 
tioned by  an  instrument  of  such  necromantic  power? 


IV 

But  the  spectroscope  is  not  alone  in  this  audacious 
assault  upon  the  strongholds  of  nature.  It  has  a  worthy 
companion  and  assistant  in  the  photographic  film,  whose 
efficient  aid  has  been  invoked  by  the  astronomer  even 
more  recently.  Pioneer  work  in  celestial  photography 
was,  indeed,  done  by  Arago  in  France  and  by  the  elder 
Draper  in  America  in  1839,  but  the  results  then  achieved 
were  only  tentative,  and  it  was  not  till  forty  years  later 
that  the  method  assumed  really  important  proportions. 

76 


3 
3 

5  S 
IB 

I  * 


rs 


OK   THK 

UNIVERSITY 


THE   CENTURY'S   PROGRESS   IN  ASTRONOMY 

In  1880  Dr.  Henry  Draper,  at  Hastings-on-the-Hudson, 
made  the  first  successful  photograph  of  a  nebula.  Soon 
after,  Dr.  David  Gill,  at  the  Cape  observatory,  made  fine 
photographs  of  a  comet,  and  the  flecks  of  starlight  on 
his  plates  first  suggested  the  possibilities  of  this  method 
in  charting  the  heavens. 

Since  then  star-charting  with  the  film  has  come  to 
virtually  supersede  the  old  method.  A  concerted  effort  is 
being  made  by  astronomers  in  various  parts  of  the  world 
to  make  a  complete  chart  of  the  heavens,  and  before 
the  close  of  our  century  this  work  will  be  accomplished, 
some  fifty  or  sixty  millions  of  visible  stars  being  placed 
on  record  with  a  degree  of  accuracy  hitherto  unapproach- 
able. Moreover,  other  millions  of  stars  are  brought  to 
light  by  the  negative  which  are  too  distant  or  dim  to  be 
visible  with  any  telescopic  powers  yet  attained — a  fact 
which  wholly  discredits  all  previous  inferences  as  to  the 
limits  of  our  sidereal  system.  Hence,  notwithstanding 
the  wonderful  instrumental  advances  of  our  century, 
knowledge  of  the  exact  form  and  extent  of  pur  universe 
seems  more  unattainable  than  it  seemed  a  century  ago. 

Yet  the  new  instruments,  while  leaving  so  much 
untold,  have  revealed  some  vastly  important  secrets  of 
cosmic  structure.  In  particular,  they  have  set  at  rest 
the  long-standing  doubts  as  to  the  real  structure  and 
position  of  the  mysterious  nebulae — those  hazy  masses, 
only  two  or  three  of  them  visible  to  the  unaided  eye, 
which  the  telescope  reveals  in  almost  limitless  abundance, 
scattered  everywhere  among  the  stars,  but  grouped  in 
particular  about  the  poles  of  the  stellar  stream  or  disk 
which  we  call  the  Milky  Way. 

Herschel's  later  view,  which  held  that  some  at  least 
of  the  nebulae  are  composed  of  a  "  shining  fluid,"  in 

79 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

process  of  condensation  to  form  stars,  was  generally 
accepted  for  almost  half  a  century.  But  in  1844,  when 
Lord  Rosse's  great  six-foot  reflector — the  largest  tele- 
scope ever  yet  constructed — was  turned  on  the  nebulae, 
it  made  this  hypothesis  seem  very  doubtful.  Just  as 
Galileo's  first  lens  had  resolved  the  Milky  Way  into 
stars,  just  as  Herschel  had  resolved  nebulae  that  resisted 
all  instruments  but  his  own,  so  Lord  Kosse's  even  greater 
reflector  resolved  others  that  would  not  yield  to  Her- 
schel's  largest  mirror.  It  seemed  a  fair  inference  that 
with  sufficient  power,  perhaps  some  clay  to  be  attained, 
all  nebulae  would  yield,  hence  that  all  are  in  reality 
what  Herschel  had  at  first  thought  them— vastly  distant 
"  island  universes,"  composed  of  aggregations  of  stars, 
comparable  to  our  own  galactic  system. 

But  the  inference  was  wrong;  for  when  the  spectro- 
scope was  first  applied  to  a  nebula  in  1864,  by  Dr.  Hug- 
gins,  it  clearly  showed  the  spectrum  not  of  discrete  stars, 
but  of  a  great  mass  of  glowing  gases,  hydrogen  among 
others.  More  extended  studies  showed,  it  is  true,  that 
some  nebulae  give  the  continuous  spectrum  of  solids  or 
liquids,  but  the  different  types  intermingle  and  grade 
into  one  another.  Also,  the  closest  affinity  is  shown  be- 
tween nebulae  and  stars.  Some  nebulae  are  found  to 
contain  stars,  singly  or  in  groups,  in  their  actual  midst ; 
certain  condensed  "planetary"  nebulae  are  scarcely  to 
be  distinguished  from  stars  of  the  gaseous  type ;  and  re- 
cently the  photographic  film  has  shown  the  presence  of 
nebulous  matter  about  stars  that  to  telescopic  vision  dif- 
fer in  no  respect  from  the  generality  of  their  fellows  in 
the  galaxy.  The  familiar  stars  of  the  Pleiades  cluster, 
for  example,  appear  on  the  negative  immersed  in  a  hazy 
blur  of  light.  All  in  all,  the  accumulated  impressions  of 

80 


IT 

"2.    23 
5     3 


a  w 
o  a 

a 


,  1 

2.    § 

II 

«     t"1 


g 

2 


THE   CENTURY'S    PROGRESS   IN  ASTRONOMY 

' 

the  photographic  film  reveal  a  prodigality  of  nebulous 
matter  in.  the  stellar  system  not  hitherto  even  con- 
jectured. 

And  so,  of  course,  all  question  of  "island  universes" 
vanishes,  and  the  nebulae  are  relegated  to  their  true  po- 
sition as  component  parts  of  the  one  stellar  system — the 
one  universe — that  is  open  to  present  human  inspection. 
And  these  vast  clouds  of  world-stuff  have  been  found 
by  Professor  Keeler,  of  the  Lick  Observatory,  to  be 
floating  through  space  at  the  starlike  speed  of  from  ten 
to  thirty-eight  miles  per  second? 

The  linking  of  nebulae  with  stars,  so  clearly  evi- 
denced by  all  these  modern  observations,  is,  after  all, 
only  the  scientific  corroboration  of  what  the  elder  Her- 
schel's  later  theories  affirmed.  But  the  nebulae  have 
other  affinities  not  until  recently  suspected ;  for  the 
spectra  of  some  of  them  are  practically  identical  with 
the  spectra  of  certain  comets.  The  conclusion  seems 
warranted  that  comets  are  in  point  of  fact  minor  nebu- 
lae that  are  drawn  into  our  system  ;  or,  putting  it  other- 
wise, that  the  telescopic  nebulae  are  simply  gigantic  dis- 
tant comets. 

Following  up  the  suprising  clews  thus  suggested,  Mr. 
J.  Norman  Lockyer,  of  London,  has  in  recent  years 
elaborated  what  is  perphaps  the  most  comprehensive 
cosmogonic  guess  that  has  ever  been  attempted.  His 
theory,  known  as  the  ''meteoric  hypothesis,"  probably 
bears  the  same  relation  to  the  speculative  thought  of 
our  time  that  the  nebular  hypothesis  of  Laplace  bore  to 
that  of  the  eighteenth  century.  Outlined  in  a  few 
words,  it  is  an  attempt  to  explain  all  the  major  phe- 
nomena of  the  universe  as  due,  directly  or  indirectly,  to 
the  gravitational  impact  of  such  meteoric  particles,  or 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

specks  of  cosmic  dust,  as  comets  are  composed  of.  Neb- 
ulae are  vast  cometary  clouds,  with  particles  more  or 
less  widely  separated,  giving  off  gases  through  meteoric 
collisions,  internal  or  external,  and  perhaps  glowing  also 
with  electrical  or  phosphorescent  light.  Gravity  eventu- 
ally brings  the  nebular  particles  into  closer  aggregations, 
and  increased  collisions  finally  vaporize  the  entire  mass, 
forming  planetary  nebulas  and  gaseous  stars.  Contin- 
ued condensation  may  make  the  stellar  mass  hotter  and 
more  luminous  for  a  time,  but  eventually  leads  to  its 
liquefaction,  and  ultimate  consolidation — the  aforetime 
nebula3  becoming  in  the  end  a  dark  or  planetary  star. 

The  exact  correlation  Avhich  Mr.  Lockyer  attempts  to 
point  out  between  successive  stages  of  meteoric  con- 
densation and  the  various  types  of  observed  stellar  bod- 
ies does  not  meet  with  unanimous  acceptance.  Mr. 
Ranyard,  for  example,  suggests  that  the  visible  nebulae 
may  not  be  nascent  stars,  but  emanations  from  stars, 
and  that  the  true  pre-stellar  nebulae  are  invisible  until 
condensed  to  stellar  proportions.  But  such  details  aside, 
the  broad  general  hypothesis  that  all  the  bodies  of  the 
universe  are,  so  to  speak,  of  a  single  species — that  neb- 
ulae (including  comets),  stars  of  all  types,  and  planets, 
are  but  varying  stages  in  the  life  history  of  a  single 
race  or  type  of  cosmic  organisms — is  accepted  by  the 
dominant  thought  of  our  time  as  having  the  highest  war- 
rant of  scientific  probability. 

All  this,  clearly,  is  but  an  amplification  of  that  nebu- 
lar hypothesis  which,  long  before  the  spectroscope  gave 
us  warrant  to  accurately  judge  our  sidereal  neighbors, 
had  boldly  imagined  the  development  of  stars  out  of 
nebular  and  of  planets  out  of  stars.  But  Mr.  Lockyer's 
hypothesis  does  not  stop  with  this.  Having  traced  the 

84 


THE   CENTURY'S   PROGRESS   IN  ASTRONOMY 

developmental  process  from  the  nebula  to  the  dark  star, 
it  sees  no  cause  to  abandon  this  dark  star  to  its  fate  by 
assuming-,  as  the  original  speculation  assumed,  that  this 
is  a  culminating  and  final  stage  of  cosmic  existence. 
For  the  dark  star,  though  its  molecular  activities  have 
come  to  relative  stability  and  impotence,  still  retains  the 
enormous  potentialities  of  molar  motion;  and  clearly, 


THE  OXFORD  HELIOMETER 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCK 

where  motion  is,  stasis  is  not.  Sooner  or  later,  in  its 
ceaseless  flight  through  space,  the  dark  star  must  col- 
lide with  some  other  stellar  body,  as  Dr.  Croll  imagines 
of  the  dark  bodies  which  his  "  pre-nebular  theory  "  pos- 
tulates. Such  collision  may  be  long  delayed ;  the  dark 
star  may  be  drawn  in  cometlike  circuit  about  thousands 
of  other  stellar  masses,  and  be  hurtled  on  thousands  of 
diverse  parabolic  or  elliptical  orbits,  before  it  chances  to 
collide — but  that  matters  not :  "  billions  are  the  units 
in  the  arithmetic  of  eternity,"  and  sooner  or  later,  we 
can  hardly  doubt,  a  collision  must  occur.  Then  without 
question  the  mutual  impact  must  shatter  both  colliding 
bodies  into  vapor,  or  vapor  combined  with  meteoric 
fragments ;  in  short,  into  a  veritable  nebula,  the  matrix 
of  future  worlds.  Thus  the  dark  star,  which  is  the  last 
term  of  one  series  of  cosmic  changes,  becomes  the  first 
term  of  another  series— at  once  a  post-nebular  and  a  pre- 
nebular  condition  ;  and  the  nebular  hypothesis,  thus  am- 
plified, ceases  to  be  a  mere  linear  scale,  and  is  rounded 
out  to  connote  an  unending  series  of  cosmic  cycles,  more 
nearly  satisfying  the  imagination. 

In  this  extended  view,  nebulae  and  luminous  stars  are 
but  the  infantile  and  adolescent  stages  of  the  life  his- 
tory of  the  cosmic  individual;  the  dark  star,  its  adult 
stage,  or  time  of  true  virility.  Or  we  may  think  of  the 
shrunken  dark  star  as  the  germ-cell,  the  pollen-grain,  of 
the  cosmic  organism.  Eeduced  in  size,  as  becomes  a 
germ-cell,  to  a  mere  fraction  of  the  nebular  body  from 
which  it  sprang,  it  yet  retains  within  its  seemingly  non- 
vital  body  all  the  potentialities  of  the  original  organism, 
and  requires  only  to  blend  with  a  fellow-cell  to  bring  a 
new  generation  into  being.  Thus  may  the  cosmic  race, 
whose  aggregate  census  makes  up  the  stellar  universe, 

86 


THE   CENTURY'S   PROGRESS   IN  ASTRONOMY 

be  perpetuated — individual  solar  systems,  such  as  ours, 
being  born,  and  growing  old,  and  dying  to  live  again  in 
their  descendants,  while  the  universe  as  a  whole  main- 
tains its  unified  integrity  throughout  all  these  internal 
mutations — passing  on,  it  may  be,  by  infinitesimal  stages, 
to  a  culmination  hopelessly  beyond  human  compre- 
hension. 


CHAPTER  III 
THE  CENTURY'S  PROGRESS  IN  PALEONTOLOGY 


EVER  since  Leonardo  da  Yinci  first  recognized  the 
true  character  of  fossils,  there  had  been  here  and  there 
a  man  who  realized  that  the  earth's  rocky  crust  is  one 
gigantic  mausoleum.  Here  and  there  a  dilettante  had 
filled  his  cabinets  with  relics  from  this  monster  crypt; 
here  and  there  a  philosopher  had  pondered  over  them— 
questioning  whether  perchance  they  had  once  been  alive, 
or  whether  they  were  not  mere  abortive  souvenirs  of 
that  time  when  the  fertile  matrix  of  the  earth  was  sup- 
posed to  have 

"teemed  at  a  birth 

Innumerous  living  creatures,  perfect  forms, 

Limbed  and  full-grown." 

Some  few  of  these  philosophers — as  Robert  Hooke  and 
Steno  in  the  seventeenth  century,  and  Moro,  Leibnitz, 
Buffon,  Whitehurst,  Werner,  Hutton,  and  others  in  the 
eighteenth — had  vaguely  conceived  the  importance  of 
fossils  as  records  of  the  earth's  ancient  history,  but  the 
wisest  of  them  no  more  suspected  the  full  import  of  the 
story  written  in  the  rocks  than  the  average  stroller  in  a 
modern  museum  suspects  the  meaning  of  the  hieroglyphs 
on  the  case  of  a  mummy. 

88 


THE   CENTURY'S   PROGRESS   IN   PALEONTOLOGY 

It  was  not  that  the  rudiments  of  this  story  are  so  very 
hard  to  decipher — though  in  truth  they  are  hard  enough 
— but  rather  that  the  men  who  made  the  attempt  had  all 
along  viewed  the  subject  through  an  atmosphere  of  pre- 
conception, which  gave  a  distorted  image.  Before  this 
image  could  be  corrected  it  was  necessary  that  a  man 
should  appear  Avho  could  see  without  prejudice,  and 
apply  sound  common-sense  to  what  he  saw.  And  such 
a  man  did  appear  towards  the  close  of  the  century  in  the 
person  of  William  Smith,  the  English  surveyor.  He 
was  a  self-taught  man,  and  perhaps  the  more  indepen- 
dent for  that,  and  he  had  the  gift,  besides  his  sharp  eyes 
and  receptive  mind,  of  a  most  tenacious  memory.  By 
exercising  these  faculties,  rare  as  they  are  homely,  he 
led  the  way  to  a  science  which  was  destined,  in  its 
later  developments,  to  shake  the  structure  of  established 
thought  to  its  foundations. 

Little  enough  did  William  Smith  suspect,  however, 
that  any  such  dire  consequences  were  to  come  of  his  act 
when  he  first  began  noticing  the  fossil  shells  that  here 
and  there  are  to  be  found  in  the  stratified  rocks  and  soils 
of  the  regions  over  which  his  surveyor's  duties  led  him. 
Nor,  indeed,  was  there  anything  of  such  apparent  revo- 
lutionary character  in  the  facts  which  he  unearthed; 
yet  in  their  implications  these  facts  were  the  most  dis- 
concerting of  any  that  had  been  revealed  since  the  day 
of  Copernicus  and  Galileo.  In  its  bald  essence  Smith's 
discovery  was  simply  this:  that  the  fossils  in  the  rocks, 
instead  of  being  scattered  haphazard,  are  arranged  in 
regular  systems,  so  that  any  given  stratum  of  rock  is 
labelled  by  its  fossil  population ;  and  that  the  order  of 
succession  of  such  groups  of  fossils  is  always  the  same  in 
any  vertical  series  of  strata  in  which  they  occur.  That 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

is  to  say,  if  fossil  A  underlies  fossil  B  in  any  given  region, 
it  never  overlies  it  in  any  other  series ;  though  a  kind  of 
fossils  found  in  one  set  of  strata  may  be  quite  omitted 
in  another.  Moreover,  a  fossil  once  having  disappeared 
never  reappears  in  any  later  stratum. 

From  these  novel  facts  Smith  drew  the  common-sense 
inference  that  the  earth  had  had  successive  populations 
of  creatures,  each  of  which  in  its  turn  had  become  extinct. 
He  partially  verified  this  inference  by  comparing  the 
fossil  shells  with  existing  species  of  similar  orders,  and 
found  that  such  as  occur  in  older  strata  of  the  rocks  had 
no  counterparts  among  living  species.  But  on  the  whole, 
being  eminently  a  practical  man,  Smith  troubled  himself 
but  little  about  the  inferences  that  might  be  drawn  from 
his  facts.  He  was  chiefly  concerned  in  using  the  key  he 
had  discovered  as  an  aid  to  the  construction  of  the  first 
geological  map  of  England  ever  attempted,  and  he  left 
to  others  the  untangling  of  any  snarls  of  thought  that 
might  seem  to  arise  from  his  discovery  of  the  succession 
of  varying  forms  of  life  on  the  globe. 

He  disseminated  his  views  far  and  wide,  however,  in 
the  course  of  his  journeyings — quite  disregarding  the 
fact  that  peripatetics  went  out  of  fashion  when  the 
printing-press  came  in— and  by  the  beginning  of  our 
century  he  had  begun  to  have  a  following  among  the 
geologists  of  England.  It  must  not  for  a  moment  be 
supposed,  however,  that  his  contention  regarding  the 
succession  of  strata  met  with  immediate  or  general  ac- 
ceptance. On  the  contrary,  it  was  most  bitterly  an- 
tagonized. For  a  long  generation  after  the  discovery 
was  made,  the  generality  of  men,  prone  as  always  to 
strain  at  gnats  and  swallow  camels,  preferred  to  believe 
that  the  fossils,  instead  of  being  deposited  in  successive, 

90 


THE   CENTURY'S   PROGRESS   IN   PALEONTOLOGY 

ages,  had  been  swept  all  at  once  into  their  present  posi- 
tions by  the  current  of  a  mighty  flood — and  that  flood, 
needless  to  say,  the  Noachian  deluge.  Just  how  the 
numberless  successive  strata  could  have  been  laid  down 
in  orderly  sequence  to  the  depth  of  several  miles  in  one 
such  fell  cataclysm  was  indeed  puzzling,  especially  after 
it  came  to  be  admitted  that  the  heaviest  fossils  were  not 
found  always  at  the  bottom  ;  but  to  doubt  that  this  had 
been  done  in  some  way  was  rank  heresy  in  the  early 
days  of  our  century. 

ii 

But  once  discovered,  William  Smith's  unique  facts  as 
to  the  succession  of  forms  in  the  rocks  would  not  down. 
There  was  one  most  vital  point,  however,  regarding 
which  the  inferences  that  seem  to  follow  from  these 
facts  needed  verification — the  question,  namely,  whether 
the  disappearance  of  a  fauna  from  the  register  in  the 
rocks  really  implies  the  extinction  of  that  fauna.  Every- 
thing really  depended  upon  the  answer  to  that  question, 
and  none  but  an  accomplished  naturalist  could  answer  it 
with  authority.  Fortunately  the  most  authoritative  nat- 
uralist of  the  time,  Georges  Cuvier,  took  the  question  in 
hand — not,  indeed,  with  the  idea  of  verifying  any  sug- 
gestion of  Smith's,  but  in  the  course  of  his  own  original 
studies — at  the  very  beginning  of  the  century,  when 
Smith's  views  were  attracting  general  attention. 

Cuvier  and  Smith  were  exact  contemporaries,  both 
men  having  been  born  in  1769,  that  "fertile  year" 
which  gave  the  world  also  Chateaubriand,  Yon  Hum- 
boldt,  Wellington,  and  Napoleon.  But  the  French  nat- 
uralist was  of  very  different  antecedents  from  the  Eng- 

91 


THE   STOKY  OF  NINETEENTH-CENTURY  SCIENCE 


GEORGES  CUVIER 


lish  surveyor.  He  was  brilliantly  educated,  had  early 
gained  recognition  as  a  scientist,  and  while  yet  a  young 
man  had  come  to  be  known  as  the  foremost  comparative 
anatomist  of  his  time.  It  was  the  anatomical  studies 
that  led  him  into  the  realm  of  fossils.  Some  bones  dug 
out  of  the  rocks  by  workmen  in  a  quarry  were  brought 
to  his  notice,  and  at  once  his  trained  eye  told  him  that 
they  were  different  from  anything  he  had  seen  before. 

93 


THE   CENTURY'S  PROGRESS   IN   PALEONTOLOGY 

Hitherto  such  bones,  when  not  entirely  ignored^  had 
been  for  the  most  part  ascribed  to  giants  of  former  days, 
or  even  to  fallen  angels.  Cuvier  soon  showed  that 
neither  giants  nor  angels  were  in  question,  but  ele- 
phants of  an  unrecognized  species.  Continuing  his 
studies,  particularly  with  material  gathered  from  g}7p- 
sum  beds  near  Paris,  he  had  accumulated,  by  the  begin- 
ning of  our  century,  bones  of  about  twenty-five  species 
of  animals  that  he  believed  to  be  different  from  any  now 
living  on  the  globe. 

The  fame  of  these  studies  went  abroad,  and  presently 
fossil  bones  poured  in  from  all  sides,  and  Cuvier's  con- 
victions that  extinct  forms  of  animals  are  represented 
among  the  fossils  was  sustained  by  the  evidence  of  many 
strange  and  anomalous  forms,  some  of  them  of  gigantic 
size.  In  1816  the  famous  Ossemenls  Fossiles,  describing 
these  novel  objects,  was  published,  and  vertebrate  paleon- 
tology became  a  science.  Among  other  things  of  great 
popular  interest  the  book  contained  the  first  authorita- 
tive description  of  the  hairy  elephant,  named  by  Cuvier 
the  mammoth,  the  remains  of  which  had  been  found 
embedded  in  a  mass  of  ice  in  Siberia  in  1802,  so  wonder- 
fully preserved  that  the  dogs  of  the  Tungusian  fisher- 
men actually  ate  its  flesh.  Bones  of  the  same  species 
had  been  found  in  Siberia  several  years  before  by  the 
naturalist  Pallas,  who  had  also  found  the  carcass  of  a 
rhinoceros  there,  frozen  in  a  mud  bank  ;  but  no  one  then 
suspected  that  these  were  members  of  an  extinct  popula- 
tion— they  were  supposed  to  be  merely  transported  relics 
of  the  flood. 

Cuvier,  on  the  other  hand,  asserted  that  these  and  the 
other  creatures  he  described  |had  lived  and  died  in  the 
region  where  their  remains  were  found,  and  that  most 

93  • 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

of  them  have  no  living  representatives  upon  the  globe. 
This,  to  be  sure,  was  nothing  more  than  William  Smith 
had  tried  all  along  to  establish  regarding  lower  forms  of 
life ;  but  great  monsters  appeal  to  the  imagination  in  a 


THE  WAllUEN   MASTODON,  FOUND  NEATC  NEWBURG, 
ON  THE  HUDSON 


way  quite  beyond  the  power  of  mere  shells  ;  so  the  an- 
nouncement of  Cuvier's  discoveries  aroused  the  interest 
of  the  entire  world,  and  the  Ossements  Fossiles  was 
accorded  a  popular  reception  seldom  given  a  work  of 
technical  science — a  reception  in  which  the  enthusiastic 
approval  of  progressive  geologists  was  mingled  with  the 
bitter  protests  of  the  conservatives. 

94 


THE  CENTURY'S   PEQGRESS   IN   PALEONTOLOGY 

IrrEngland  the  interest  thus  aroused  was  sent  to  fever- 
heat  in  1821  by  the  discovery  of  abundant  beds  of  fossil 
bones  in  the  stalagmite-covered  floor  of  a  cave  at  Kirk- 
dale,  Yorkshire,  which  went  to  show  that  England  too 
had  once  had  her  share  of  gigantic  beasts.  Dr.  Buck- 
land,  the  incumbent  of  the  recently  established  chair  of 
geology  at  Oxford,  and  the  most  authoritative  English 
geologist  of  the  day, took  these  finds  in  hand  and  showed 
that  the  bones  belonged  to  a  number  of  species,  including 
such  alien  forms  as  elephants,  rhinoceroses,  hippopotami, 
and  hyenas.  He  maintained  that  all  of  these  creatures 
had  actually  lived  in  Britain,  and  that  the  caves  in  which 
their  bones  were  found  had  been  the  dens  of  hyenas. 

The  claim  was  hotly  disputed  as  a  matter  of  course. 
As  late  as  1827  books  were  published  denouncing  Buck- 
land,  Doctor  of  Divinity  though  he  was,  as  one  who  had 
joined  in  an  "  unhallowed  cause,"  and  reiterating  the  old 
cry  that  the  fossils  were  only  remains  of  tropical  species 
washed  thither  by  the  deluge.  That  they  were  found 
in  solid  rocks  or  in  caves  offered  no  difficulty,  at  least 
not  to  the  fertile  imagination  of  Granville  Penn,  the 
leader  of  the  conservatives,  who  clung  to  the  old  idea 
of  Woodward  and  Cattcut  that  the  deluged  ha  dissolved 
the  entire  crust  of  the  earth  to  a  paste,  into  which  the 
relics  now  called  fossils  had  settled.  The  caves,  said 
Mr.  Penn,  are  merely  the  result  of  gases  given  off  by 
the  carcasses  during  decomposition— great  air-bubbles, 
so  to  speak,  in  the  pasty  mass  becoming  caverns  when 
the  waters  receded  and  the  paste  hardened  to  rocky 
consistency. 

But  these  and  such  like  fanciful  views  were  doomed 
even  in  the  day  of  their  utterance.  Already  in  1823  other 
gigantic  creatures,  christened  ichthyosaurus  and  plesio- 

95 


THE   STORY   OF   NINETEENTH-CENTURY  SCIENCE 

saurus  by  Conybeare,  had  been  found  in  deeper  strata  of 
British  rocks;  and  these,  as  well  as  other  monsters  whose 
remains  were  unearthed  in  various  parts  of  the  world, 
bore  such  strange  forms  that  even  the  most  sceptical 
could  scarcely  hope  to  find  their  counterparts  among 
living  creatures.  Cuvier's  contention  that  all  the  larger 


SKULL,  LACKING  JAW,  OF   EOBASILEUS  CORNUTUS,  COPE 

vertebrates  of  the  existing  age  are  known  to  naturalists 
was  borne  out  by  recent  explorations,  and  there  seemed 
no  refuge  from  the  conclusion  that  the  fossil  records 
tell  of  populations  actually  extinct.  But  if  this  were 

96 


THE   CENTURY'S   PROGRESS   IN   PALEONTOLOGY 

admitted,  then  Smith's  view  that  there  have  been  suc- 
cessive rotations  of  population  could  no  longer  be  denied. 
Nor  could  it  be  in  doubt  that  the  successive  faunas,  whose 
individual  remains  have  been  preserved  in  myriads,  rep- 
resenting extinct  species  by  thousands  and  tens  of  thou- 
sands, must  have  required  vast  periods  of  time  for  the 
production  and  growth  of  their  countless  generations. 

As  these  facts  came  to  be  generally  known,  and  as  it 
came  to  be  understood  in  addition  that  the  very  matrix 
of  the  rock  in  which  fossils  are  embedded  is  in  many 
cases  itself  one  gigantic  fossil,  composed  of  the  remains 
of  microscopic  forms  of  life,  common-sense,  which,  after 
all,  is  the  final  tribunal,  came  to  the  aid  of  belabored 
science.  It  was  conceded  that  the  only  tenable  inter- 
pretation of  the  record  in  the  rocks  is  that  numerous 
populations  of  creatures,  distinct  from  one  another  and 
from  present  forms,  have  risen  and  passed  away;  and 
that  the  geologic  ages  in  which  these  creatures  lived 
were  of  inconceivable  length.  The  rank  and  file  came 
thus,  with  the  aid  of  fossil  records,  to  realize  the  import 
of  an  idea  which  James  Hutton,  and  here  and  there 
another  thinker,  had  conceived  with  the  swift  intuition 
of  genius  long  before  the  science  of  paleontology  came 
into  existence.  The  Huttonian  proposition  that  time  is 
long  had  been  abundantly  established,  and  by  about  the 
close  of  the  first  third  of  our  century  geologists  had 
begun  to  speak  of  "ages"  and  "untold  asons  of  time" 
with  a  familiarity  which  their  predecessors  had  reserved 
for  days  and  decades. 

in 

And  now  a  new  question  pressed  for  solution.     If  the 
earth  has  been  inhabited  by  successive  populations  of 
G  97 


THE   STORY  OF  NINETEENTH-CEN1URY  SCIENCE 

beings  now  extinct,  how  have  all  these  creatures  been 
destroyed  ?  That  question,  however,  seemed  to  present 
no  difficulties.  It  was  answered  out  of  hand  by  the 
application  of  an  old  idea.  All  down  the  centuries, 
whatever  their  varying  phases  of  cosmogonic  thought, 
there  had  been  ever  present  the  idea  that  past  times 
were  not  as  recent  times ;  that  in  remote  epochs  the 
earth  had  been  the  scene  of  awful  catastrophes  that 
have  no  parallel  in  "these  degenerate  days."  Naturally 
enough  this  thought,  embalmed  in  every  cosmogonic 
speculation  of  whatever  origin,  was  appealed  to  in 
explanation  of  the  destruction  of  these  hitherto  un im- 
agined hosts,  which  now,  thanks  to  science,  rose  from 
their  abysmal  slumber  as  incontestable,  but  also  as  silent 
and  as  thought -pro  vocative  as  Sphinx  or  pyramid. 
These  ancient  hosts,  it  was  said,  have  been  exterminated 
at  intervals  of  odd  millions  of  years  by  the  recurrence 
of  catastrophes  of  which  the  Mosaic  deluge  is  the  latest, 
but  perhaps  not  the  last. 

This  explanation  had  fullest  warrant  of  scientific  au- 
thority. Cuvier  had  prefaced  his  classical  work  with  a 
speculative  disquisition  whose  very  title  (Discours  sur  les 
Revolutions  du  Globe)  is  ominous  of  catastrophism,  and 
whose  text  fully  sustains  the  augury.  And  Buckland, 
Cuvier's  foremost  follower  across  the  Channel,  had  gone 
even  beyond  the  master,  naming  the  work  in  which  he 
described-  the  Kirkdale  fossils,  ReliquicB  Diluviance,  or 
Proofs  of  a  Universal  Deluge. 

Both  these  authorities  supposed  the  creatures  whose 
remains  they  studied  to  have  perished  suddenly  in  the 
mighty  flood  whose  awful  current,  as  they  supposed, 
gouged  out  the  modern  valleys,  and  hurled  great  blocks 
of  granite  broadcast  over  the  land.  And  they  invoked 


THE   CENTURY'S   PROGRESS   IN  PALEONTOLOGY 

similar  floods  for  the  extermination  of  previous  popula- 
tions. 

It  is  true  these  scientific  citations  had  met  with  only 
qualified  approval  at  the  time  of  their  utterance,  because 
then  the  conservative  majority  of  mankind  did  not  con- 
cede that  there  had  been  a  plurality  of  populations  or 
revolutions;  but  now  that  the  belief  in  past  geologic 
ages  had  ceased  to  be  a  heresy,  the  recurring  catastro- 
phes of  the  great  paleontologists  were  accepted  with 
acclaim.  For  the  moment  science  and  tradition  were  at 
one,  and  there  was  a  truce  to  controversy,  except  indeed 
in  those  outlying  skirmish-lines  of  thought  whither  news 
from  headquarters  does  not  permeate  till  it  has  become 
ancient  history  at  its  source. 

The  truce,  however,  was  not  for  long.  Hardly  had 
contemporary  thought  begun  to  adjust  itself  to  the 
conception  of  past  ages  of  incomprehensible  extent, 
each  terminated  by  a  catastrophe  of  the  Noachian 
type,  when  a  man  appeared  who  made  the  utterly  be- 
wildering assertion  that  the  geological  record,  instead 
of  proving  numerous  catastrophic  revolutions  in  the 
earth's  past  history,  gives  no  warrant  to  the  preten- 
sions of  any  universal  catastrophe  whatever,  near  or 
remote. 

This  iconoclast  was  Charles  Lyell,  the  Scotchman,  who 
was  soon  to  be  famous  as  the  greatest  geologist  of  his 
time.  As  a  young  man  he  had  become  imbued  with  the 
force  of  the  Huttonian  proposition,  that  present  causes 
are  one  with  those  that  produced  the  past  changes  of 
the  globe,  and  he  carried  that  idea  to  what  he  conceived 
to  be  its  logical  conclusion.  To  his  mind  this  excluded 
the  thought  of  catastrophic  changes  in  either  inorganic 
or  organic  worlds. 

99 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

But  to  deny  catastrophism  was  to  suggest  a  revolu- 
tion in  current  thought.  Needless  to  say  such  revolu- 
tion could  not  be  effected  without  a  long  contest.  For 
a  score  of  years  the  matter  was  argued  pro  and  con, 
often  with  most  unscientific  ardor.  A  mere  outline  of 
the  controversy  would  fill  a  volume;  yet  the  essential 
facts  with  which  Lyell  at  last  established  his  proposi- 
tion, in  its  bearings  on  the  organic  world,  may  be  epito- 
mized in  few  words.  The  evidence  which  seems  to  tell 
of  past  revolutions  is  the  apparently  sudden  change  of 
fossils  from  one  stratum  to  another  of  the  rocks.  But 
Lyell  showed  that  this  change  is  not  always  com- 
plete. Some  species  live  on  from  one  alleged  epoch 
into  the  next.  By  no  means  all  the  contemporaries 
of  the  mammoth  are  extinct,  and  numerous  marine 
forms  vastly  more  ancient  still  have  living  represent- 
atives. 

Moreover,  the  blanks  between  strata  in  any  particular 
vertical  series  are  amply  filled  in  with  records  in  the 
form  of  thick  strata  in  some  geographically  distant 
series.  For  example,  in  some  regions  Silurian  rocks  are 
directly  overlaid  by  the  coal  measures ;  but  elsewhere 
this  sudden  break  is  filled  in  with  the  Devonian  rocks 
that  tell  of  a  great  "  age  of  fishes."  So  commonly  are 
breaks  in  the  strata  in  one  region  filled  up  in  another, 
that  we  are  forced  to  conclude  that  the  record  shown 
by  any  single  vertical  series  is  of  but  local  significance- 
telling,  perhaps,  of  a  time  when  that  particular  sea-bed 
oscillated  above  the  water-line,  and  so  ceased  to  receive 
sediment  until  some  future  age  when  it  had  oscillated 
back  again.  But  if  this  be  the  real  significance  of  the 
seemingly  sudden  change  from  stratum  to  stratum,  then 
the  whole  case  for  catastrophism  is  hopelessly  lost ;  for 

100 


THE   CENTURY'S   PROGRESS   IN   PALEONTOLOGY 

such  breaks  in  the  strata  furnish  the  only  suggestion 
geology  can  offer  of  sudden  and  catastrophic  changes  of 
wide  extent. 

When  evidence  from  widely  separated  regions  is 
gathered,  said  Lyell,  it  becomes  clear  that  the  number- 
less species  that  have  been  exterminated  in  the  past 


METAMYNODON,   OR   SWIMMING   RHINOCEROS,  FROM   SOUTH   DAKOTA 

have  died  out  one  by  one,  just  as  individuals  of  a  species 
die,  not  in  vast  shoals  ;  if  whole  populations  have  passed 
away,  it  has  been  not  by  instantaneous  extermination, 
but  by  the  elimination  of  a  species  now  here,  now  there, 
much  as  one  generation  succeeds  another  in  the  life  his- 
tory of  any  single  species.  The  causes  which  have 
brought  about  such  gradual  exterminations,  and  in  the 
long  lapse  of  ages  have  resulted  in  rotations  of  popula- 
tion, are  the  same  natural  causes  that  are  still  in  opera- 
tion. Species  have  died  out  in  the  past  as  they  are 
dying  out  in  the  present,  under  influence  of  changed 

101 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

surroundings,  such  as  altered  climate,  or  the  migration 
into  their  territory  of  more  masterful  species.  Past  and 
present  causes  are  one — natural  law  is  changeless  and 
eternal. 

Such  was  the  essence  of  the  Huttonian  doctrine,  which 
Lyell  adopted  and  extended,  and  with  which  his  name 
will  always  be  associated.  Largely  through  his  efforts, 
though  of  course  not  without  the  aid  of  many  other 
workers  after  a  time,  this  idea — the  doctrine  of  uniform- 
itarianism,  it  came  to  be  called — became  the  accepted 
dogma  of  the  geologic  world  not  long  after  the  middle 
of  our  century.  The  catastrophists,  after  clinging  madly 
to  their  phantom  for  a  generation,  at  last  capitulated 
without  terms:  the  old  heresy  became  the  new  ortho- 
doxy, and  the  way  was  paved  for  a  fresh  controversy. 


IV 

The  fresh  controversy  followed  quite  as  a  matter  of 
course.  For  the  idea  of  catastrophism  had  not  con- 
cerned the  destruction  of  species  merely,  but  their  intro- 
duction as  well.  If  whole  faunas  had  been  extirpated 
suddenly,  new  faunas  had  presumably  been  introduced 
with  equal  suddenness  by  special  creation  ;  but  if  species 
die  out  gradually,  the  introduction  of  new  species  may 
be  presumed  to  be  correspondingly  gradual.  Then  may 
not  the  new  species  of  a  later  geological  epoch  be  the 
modified  lineal  descendants  of  the  extinct  population  of 
an  earlier  epoch  ? 

The  idea  that  such  might  be  the  case  was  not  new. 
It  had  been  suggested  when  fossils  first  began  to  attract 
conspicuous  attention;  and  such  sagacious  thinkers  as 
Buffon  and  Kant  and  Goethe  and  Erasmus  Darwin  had 

103 


THE   CENTURY'S   PROGRESS   IN   PALEONTOLOGY 


been  disposed  to  accept  it  in  the  closing  days  of  the 
eighteenth  century.  Then,  in  1809,  it  had  been  con- 
tended for  by  one  of  the  early  workers  in  systematic 
paleontology,  Jean  Baptiste  Lamarck,  who  had  studied 
the  fossil  shells  about  Paris  while  Cuvier  studied  the 
vertebrates,  and  who  had  been  led  by  these  studies  to 
conclude  that  there  had  been  not  merely  a  rotation  but 
a  progression  of  life  on  the  globe.  He  found  the  fossil 
shells- -the  fossils  of  invertebrates,  as  he  himself  had 
christened  them — in  deeper  strata  than  Cuvier's  verte- 
brates; and  he  believed  that  there  had  been  long  ages 


HYRACHYUS,  OR  RUNNING   RHINOCEROS,   PROM  SOUTHERN  WYOMING 

when  no  higher  forms  than  these  were  in  existence,  and 
that  in  successive  ages  fishes,  and  then  reptiles,  had  been 
the  highest  of  animate  creatures,  before  mammals,  in- 
cluding man,  appeared.  Looking  beyond  the  pale  of  his 
bare  facts,  as  genius  sometimes  will,  he  had  insisted  that 
these  progressive  populations  had  developed  one  from 

103 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

another,  under  influence  of  changed  surroundings,  in 
unbroken  series. 

Of  course  such  a  thought  as  this  was  hopelessly  mis- 
placed in  a  generation  that  doubted  the  existence  of  ex- 
tinct species,  and  hardly  less  so  in  the  generation  that 
accepted  catastrophism ;  but  it  had  been  kept  alive  by 
here  and  there  an  advocate  like  Geoffrey  St.-Hilaire, 
and  now  the  banishment  of  catastrophism  opened  the 
way  for  its  more  respectful  consideration.  Respectful 
consideration  was  given  it  by  Lyell  in  each  recurring 
edition  of  his  Principles,  but  such  consideration  led  to 
its  unqualified  rejection.  In  its  place  Lyell  put  forward 
a  modified  hypothesis  of  special  creation.  He  assumed 
that  from  time  to  time,  as  the  extirpation  of  a  species 
had  left  room,  so  to  speak,  for  a  new  species,  such  new 
species  had  been  created  de  novo  ;  and  he  supposed  that 
such  intermittent,  spasmodic  impulses  of  creation  mani- 
fest themselves  nowadays  quite  as  frequently  as  at  any 
time  in  the  past.  He  did  not  say  in  so  many  words 
that  no  one  need  be  surprised  to-day  were  he  to  see  a 
new  species  of  deer,  for  example,  come  up  out  of  the 
ground  before  him,  "  pawing  to  get  free,"  like  Milton's 
lion,  but  his  theory  implied  as  much.  And  that  theory, 
let  it  be  noted,  was  not  the  theory  of  Lyell  alone,  but 
of  nearly  all  his  associates  in  the  geologic  world.  There 
is  perhaps  no  other  fact  that  will  bring  home  to  one  so 
vividly  the  advance  in  thought  of  our  own  generation 
as  the  recollection  that  so  crude,  so  almost  unthinkable  a 
conception  could  have  been  the  current  doctrine  of  sci- 
ence less  than  half  a  century  ago. 

This  theory  of  special  creation,  moreover,  excluded 
the  current  doctrine  of  uniformitarianism  as  night  ex- 
cludes day,  though  most  thinkers  of  the  time  did  not 

104 


THE   CENTURY'S   PROGRESS   IN   PALEONTOLOGY 

seem  to  be  aware  of  the  incompatibility  of  the  two 
ideas.  It  may  be  doubted  whether  even  Lyell  himself 
fully  realized  it.  If  he  did,  he  saw  no  escape  from  the 
dilemma,  for  it  seemed  to  him  that  the  record  in  the 
rocks  clearly  disproved  the  alternative  Lamarckian  hy- 
pothesis. And  almost  with  one  accord  the  paleontolo- 
gists of  the  time  sustained  the  verdict.  Owen,  Agassiz, 
Falconer,  Barrande,  Pictet,  Forbes,  repudiated  the  idea 
as  unqualifiedly  as  their  great  predecessor  Cuvier  had 
done  in  the  earlier  generation.  Some  of  them  did,  in- 
deed, come  to  believe  that  there  is  evidence  of  a  pro- 
gressive development  of  life  in  the  successive  ages,  but 
no  such  graded  series  of  fossils  had  been  discovered  as 
would  give  countenance  to  the  idea  that  one  species  had 
ever  been  transformed  into  another.  And  to  nearly 
every  one  this  objection  seemed  insuperable. 

But  now  in  1859  appeared  a  book  which,  though  not 
dealing  primarily  with  paleontology,  yet  contained  a 
chapter  that  revealed  the  geological  record  in  an  alto- 
gether new  light.  The  book  was  Charles  Darwin's  Ori- 
gin of  Species,  the  chapter  that  wonderful  citation  of 
the  "  Imperfections  of  the  Geological  Eecord."  In  this 
epoch-making  chapter  Darwin  shows  what  conditions 
must  prevail  in  any  given  place  in  order  that  fossils 
shall  be  formed,  how  unusual  such  conditions  are,  and 
how  probable  it  is  that  fossils  once  embedded  in  sedi- 
ment of  a  sea-bed  will  be  destroyed  by  metamorphosis 
of  the  rocks,  or  by  denudation  when  the  strata  are 
raised  above  the  water-level.  Add  to  this  the  fact  that 
only  small  territories  of  the  earth  have  been  explored 
geologically,  he  says,  and  it  becomes  clear  that  the 
paleontological  record  as  we  now  possess  it  shows  but  a 
mere  fragment  of  the  past  history  of  organisms  on  the 

105 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

earth.  It  is  a  history  "  imperfectly  kept  and  written  in 
a  changing  dialect.  Of  this  history  we  possess  the  last 
volume  alone,  relating  only  to  two  or  three  countries. 
Of  this  volume  only  here  and  there  a  short  chapter  has 


PROFESSOR  E.    D.    COPE 


been  preserved,  and  of  each  page  only  here  and  there  a 
few  lines."  For  a  paleontologist  to  dogmatize  from 
such  a  record  would  be  as  rash,  he  thinks,  as  "  for  a  nat- 
uralist to  land  for  five  minutes  on  a  barren  point  of 


THE   CENTURY'S   PROGRESS   IN   PALEONTOLOGY 

Australia  and  then  discuss  the  number  and  range  of  its 
productions." 

This  citation  of  observations,  which  when  once  point- 
ed out  seemed  almost  self-evident,  came  as  a  revelation 
to  the  geological  world.  In  the  clarified  view  now  pos- 
sible old  facts  took  on  a  new  meaning.  It  was  recalled 
that  Cuvier  had  been  obliged  to  establish  a  new  order 
for  some  of  the  first  fossil  creatures  he  examined,  and 
that  Buckland  had  noted  that  the  nondescript  forms  were 
intermediate  in  structure  between  allied  existing  orders. 
More  recently  such  intermediate  forms  had  been  discov- 
ered over  and  over;  so  that,  to  name  but  one  example, 
Owen  had  been  able,  with  the  aid  of  extinct  species,  to 
"dissolve  by  gradations  the  apparently  wide  interval 
between  the  pig  and  the  camel."  Owen,  moreover,  had 
been  led  to  speak  repeatedly  of  the  "  generalized  forms '' 
of  extinct  animals,  and  Agassiz  had  called  them  "  syn- 
thetic or  prophetic  types,"  these  terms  clearly  implying 
"  that  such  forms  are  in  fact  intermediate  or  connecting 
links."  Darwin  himself  had  shown  some  years  before 
that  the  fossil  animals  of  any  continent  are  closely  re- 
lated to  the  existing  animals  of  that  continent — eden- 
tates predominating,  for  example,  in  South  America, 
and  marsupials  in  Australia.  Many  observers  had  noted 
that  recent  strata  everywhere  show  a  fossil  fauna  more 
nearly  like  the  existing  one  than  do  more  ancient  strata; 
and  that  fossils  from  any  two  consecutive  strata  are  far 
more  closely  related  to  each  other  than  are  the  fossils 
of  two  remote  formations,  the  fauna  of  each  geological 
formation  being,  indeed,  in  a  wide  view,  intermediate 
between  preceding  and  succeeding  faunas. 

So  suggestive  were  all  these  observations  that  Lyell, 
the  admitted  leader  of  the  geological  world,  after  read- 

107 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

ing  Darwin's  citations,  felt  able  to  drop  his  own  crass 
explanation  of  the  introduction  of  species,  and  adopt 
the  transmutation  hypothesis,  thus  rounding  out  the 
doctrine  of  uniformitarianism  to  the  full  proportions  in 
which  Lamarck  had  conceived  it  half  a  century  before. 
Not  all  paleontologists  could  follow  him  at  once,  of 
course ;  the  proof  was  not  yet  sufficiently  demonstative 
for  that;  but  all  were  shaken  in  the  seeming  security 
of  their  former  position,  which  is  always  a  necessary 
stage  in  the  progress  of  thought.  And  popular  inter- 
est in  the  matter  was  raised  to  white  heat  in  a  twin- 
kling. 

So,  for  the  third  time  in  this  first  century  of  its  ex- 
istence, paleontology  was  called  upon  to  play  a  leading 
role  in  a  controversy  whose  interest  extended  far  be- 
yond the  bounds  of  staid  truth-seeking  science.  And 
the  controversy  waged  over  the  age  of  the  earth  had 
not  been  more  bitter,  that  over  catastrophism  not  more 
acrimonious,  than  that  which  now  raged  over  the  ques- 
tion of  the  transmutation  of  species.  The  question  had 
implications  far  beyond  the  bounds  of  paleontology,  of 
course.  The  main  evidence  yet  presented  had  been 
drawn  from  quite  other  fields,  but  by  common  consent 
the  record  in  the  rocks  might  furnish  a  crucial  test  of 
the  truth  or  falsity  of  the  hypothesis.  "  He  who  rejects 
this  view  of  the  imperfections  of  the  geological  rec- 
ord," said  Darwin,  "will  rightly  reject  the  whole 
theory." 

With  something  more  than  mere  scientific  zeal,  there- 
fore, paleontologists  turned  anew  to  the  records  in  the 
rocks,  to  inquire  what  evidence  in  proof  or  refutation 
might  be  found  in  unread  pages  of  the  "  great  stone 
book."  And  as  might  have  been  expected,  many  minds 

108 


THE  CENTURY'S   PROGRESS   IN   PALEONTOLOGY 

being  thus  prepared  to  receive  new  evidence,  such  evi- 
dence was  not  long  withheld. 


Indeed,  at  the  moment  of  Darwin's  writing  a  new 
and  very  instructive  chapter  of  the  geologic  record  was 
being  presented  to  the  public — a  chapter  which  for  the 
first  time  brought  man  into  the  story.  In  1859  Dr. 
Falconer,  the  distinguished  British  paleontologist,  made 
a  visit  to  Abbeville,  in  the  valley  of  the  Somme,  incited 
by  reports  that  for  a  decade  before  had  been  sent  out 
from  there  by  M.  Boucher  des  Perthes.  These  reports 
had  to  do  with  the  alleged  finding  of  flint  implements, 
clearly  the  work  of  man,  in  undisturbed  gravel  beds,  in 
the  midst  of  fossil  remains  of  the  mammoth  and  other 
extinct  animals.  Dr.  Falconer  was  so  much  impressed 
with  what  he  saw  that  he  urged  his  countrymen  Pro- 
fessor Prestwich  to  go  to  Abbeville  and  thoroughly  in- 
vestigate the  subject.  Professor  Prestwich  complied, 
with  the  collaboration  of  Mr.  John  Evans,  and  the  re- 
port which  these  paleontologists  made  of  their  investi- 
gation brought  the  subject  of  the  very  significant  human 
fossils  at  Abbeville  prominently  before  the  public; 
whereas  the  publications  of  the  original  discoverer, 
Boucher  des  Perthes,  bearing  date  of  1847,  had  been  al- 
together ignored.  A  new  aspect  was  thus  given  to  the 
current  controversy. 

As  Dr.  Falconer  remarked,  geology  was  now  passing 
through  the  same  ordeal  that  astronomy  passed  in  the 
age  of  Galileo.  But  the  times  were  changed  since  the 
day  when  the  author  of  the  Dialogues  was  humbled  be- 
fore the  Congregation  of  the  Index,  and  now  no  Index 

109 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

Prohibitorum  could  avail  to  bide  from  eager  human 
eyes  sucb  pages  of  the  geologic  story  as  Nature  herself 
had  spared.  Eager  searchers  were  turning  the  leaves 
with  renewed  zeal  everywhere,  and  with  no  small  meas- 
ure of  success.  In  particular,  interest  attached  just  at 
this  time  to  a  human  skull  which  Dr.  Fuhlrott  had  dis- 


PROTOROHIPPUS,   THE   ANCESTRAL   FOUR-TOED   HORSE 

Height  at  shoulder,  16  inches.     From  the  Big  Horn  Mountains 

covered  in  a  cave  at  Neanderthal  two  or  three  years  be- 
fore— a  cranium  which  has  ever  since  been  famous  as 
the  Neanderthal  skull,  the  type  specimen  of  what  mod- 
ern zoologists  are  disposed  to  regard  as  a  distinct  spe- 
cies of  man,  Homo  neanderthalensis.  Like  others  of  the 
same  type  since  discovered  at  Spy,  it  is  singularly  Simian 
in  character — low-arched,  with  receding  forehead  and 
enormous  protuberant  eyebrows.  When  it  was  first  ex- 
hibited to  the  scientists  at  Berlin  by  Dr.  Fuhlrott,  in 
185T,  its  human  character  was  doubted  by  some  of  the 
witnesses  •  of  that,  however,  there  is  no  present  question. 

110 


THE   CENTURY'S   PROGRESS   IN  PALEONTOLOGY 

This  interesting  find  served  to  recall  with  fresh  signifi- 
cance some  observations  that  had  been  made  in  France 
and  Belgium  a  long  generation  earlier,  but  whose  bear- 
ings had  hitherto  been  ignored.  In  1826  MM.  Tournal 
and  Christol  had  made  independent  discoveries  of  what 
they  believed  to  be  human,  fossils  in  the  caves  of  the 
south  of  France ;  and  in  1827  Dr.  Schmerling  had 
found  in  the  cave  of  Engis,  in  Westphalia,  fossil  bones 
jof  even  greater  significance.  Schmerling's  explorations 
had  been  made  with  the  utmost  care  and  patience.  At 
Engis  he  had  found  human  bones,  including  skulls,  in- 
termingled with  those  of  extinct  mammals  of  the  mam- 
moth period  in  a  way  that  left  no  doubt  in  his  mind 
that  all  dated  from  the  same  geological  epoch.  He  had 
published  a  full  account  of  his  discoveries  in  an  elaborate 
monograph  issued  in  1833. 

But  at  that  time,  as  it  chanced,  human  fossils  were  un- 
der a  ban  as  effectual  as  any  ever  pronounced  by  canonical 
index,  though  of  far  different  origin.  The  oracular  voice 
of  Cuvier  had  declared  against  the  authenticity  of  all  hu- 
man fossils.  Some  of  the  bones  brought  him  for  exam- 
ination the  great  anatomist  had  pettishly  pitched  out  of 
the  window,  declaring  them  fit  only  for  a  cemetery,  and 
that  had  settled  the  matter  for  a  generation  :  the  evi- 
dence gathered  by  lesser  workers  could  avail  nothing 
against  the  decision  rendered  at  the  Delphi  of  Science. 
But  no  ban,  scientific  or  canonical,  can  long  resist  the 
germinative  power  of  a  fact,  and  so  now,  after  three 
decades  of  suppression,  the  truth  which  Cuvier  had 
buried  beneath  the  weight  of  his  ridicule  burst  its 
bonds,  and  fossil  man  stood  revealed,  if  not  as  a  flesh 
and  blood,  at  least  as  a  skeletal  entity. 

The  reception  now  accorded  our  prehistoric  ancestor 

111 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

by  the  progressive  portion  of  the  scientific  world  amount- 
ed to  an  ovation  ;  but  the  unscientific  masses,  on  the  other 
hand,  notwithstanding  their  usual  fondness  for  tracing 
remote  genealogies,  still  gave  the  men  of  Engis  and 


PROFESSOR   O.    C.    MARSH 


Neanderthal  the  cold  shoulder.  Nor  were  all  of  the  geol- 
ogists quite  agreed  that  the  contemporaneity  of  these  hu- 
man fossils  with  the  animals  whose  remains  had  been 
mingled  with  them  had  been  fully  established.  The 
bare  possibility  that  the  bones  of  man  and  of  animals 

112 


THE   CENTURY'S   PROGRESS   IN  PALEONTOLOGY 

that  long  preceded  him  had  been  swept  together  into 
the  caves  in  successive  ages,  and  in  some  mysterious 
way  intermingled  there,  was  clung  to  by  the  conserva- 
tives as  a  last  refuge.  But  even  this  small  measure  of 
security  was  soon  to  be  denied  them,  for  in  1865  two  as- 
sociated workers,  M.  Edouard  Lartet  and  Mr.  Henry 
Christy,  in  exploring  the  caves  of  Dordogne,  unearthed 
a  bit  of  evidence  against  which  no  such  objection  could 
be  urged.  This  momentous  exhibit  was  a  bit  of  ivory, 
a  fragment  of  the  tusk  of  a  mammoth,  on  which  was 
scratched  a  rude  but  unmistakable  outline  portrait  of 
the  mammoth  itself.  If  all  the  evidence  as  to  man's 
antiquity  before  presented  was  suggestive  merely,  here 
at  last  was  demonstration  ;  for  the  cave-dwelling  man 
could  not  well  have  drawn  the  picture  of  the  mammoth 
unless  he  had  seen  that  animal,  and  to  admit  that  man 
and  the  mammoth  had  been  contemporaries  was  to  con- 
cede the  entire  case.  So  soon,  therefore,  as  the  full  im- 
port of  this  most  instructive  work  of  art  came  to  be 
realized,  scepticism  as  to  man's  antiquity  was  silenced 
for  all  time  to  come. 

In  the  generation  that  has  elapsed  since  the  first  draw- 
ing of  the  cave-dweller  artist  was  discovered,  evidences 
of  the  wide-spread  existence  of  man  in  an  early  epoch 
have  multiplied  indefinitely,  and  to-day  the  paleontolo- 
gist traces  the  history  of  our  race  back  beyond  the  iron 
and  bronze  ages,  through  a  neolithic  or  polished-stone 
age,  to  a  paleolithic  or  rough-stone  age,  with  confidence 
born  of  unequivocal  knowledge.  And  he  looks  confi- 
dently to  the  future  explorer  of  the  earth's  fossil  records 
to  extend  the  history  back  into  vastly  more  remote 
epochs,  for  it  is  little  doubted  that  paleolithic  man,  the 
most  ancient  of  our  recognized  progenitors,  is  a  modern 


o 
H  113 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

compared  to  those  generations  that  represented  the  real 
childhood  of  our  race. 


VI 

Coincidently  with  the  discovery  of  these  highly  sug- 
gestive pages  of  the  geologic  story,  other  still  more  in- 
structive chapters  were  being  brought  to  light  in  Amer- 
ica. It  was  found  that  in  the  Rocky  Mountain  region, 
in  strata  found  in  ancient  lake  beds,  records  of  the 
tertiary  period,  or  age  of  mammals,  had  been  made  and 
preserved  with  fulness  not  approached  in  any  other 
region  hitherto  geologically  explored.  These  records 
were  made  known  mainly  by  Professors  Joseph  Leidy, 
O.  C.  Marsh,  and  E.  D.  Cope,  working  independently, 
and  more  recently  by  numerous  younger  paleontolo- 
gists. 

The  profusion  of  vertebrate  remains  thus  brought  to 
light  quite  beggars  all  previous  exhibits  in  point  of  mere 
numbers.  Professor  Marsh,  for  example,  who  was  first 
in  the  field,  found  300  new  tertiary  species  between  the 
years  1870  and  1876.  Meanwhile,  in  cretaceous  strata, 
he  unearthed  remains  of  about  200  birds  with  teeth,  600 
pterodactyls,  or  flying  dragons,  some  with  a  spread  of 
wings  of  twenty-five  feet,  and  1500  mosasaurs  of  the 
sea-serpent  type,  some  of  them  sixty  feet  or  more  in 
length.  In  a  single  bed  of  Jurassic  rock,  not  larger 
than  a  good-sized  lecture-room,  he  found  the  remains 
of  160  individuals  of  mammals,  representing  twenty 
species  and  nine  genera ;  while  beds  of  the  same  age 
have  yielded  300  reptiles,  varying  from  the  size  of  a 
rabbit  to  sixty  or  eighty  feet  in  length. 

But  the  chief  interest  of  these  fossils  from  the  West  is 

114 


OF    THK 

UNIVERSITY 


THE   CENTURY'S  PROGRESS  IN  PALEONTOLOGY 

not  their  number  but  their  nature ;  for  among  them  are 
numerous  illustrations  of  just  such  intermediate  types  of 
organisms  as  must  have  existed  in  the  past  if  the  suc- 
cession of  life  on  the  globe  has  been  an  unbroken  lineal 
succession.  Here  are  reptiles  with  bat-like  wings,  and 
others  with  bird-like  pelves  and  legs  adapted  for  bipedal 
locomotion.  Here  are  birds  with  teeth  and  other  rep- 
tilian characters.  In  short,  what  with  reptilian  birds 
and  bird-like  reptiles,  the  gap  between  modern  reptiles 
and  birds  is  quite  bridged  over.  In  a  similar  way,  vari- 
ous diverse  mammalian  forms,  as  the  tapir,  the  rhinoc- 
eros, and  the  horse,  are  linked  together  by  fossil  pro- 
genitors. And  most  important  of  all,  Professor  Marsh 
has  discovered  a  series  of  mammalian  remains,  occurring 
in  successive  geological  epochs,  which  are  held  to  repre- 
sent beyond  cavil  the  actual  line  of  descent  of  the  modern 
horse ;  tracing  the  lineage  of  our  one-toed  species  back 
through  two  and  three  toed  forms,  to  an  ancestor  in  the 
eocene  or  early  tertiary  that  had  four  functional  toes 
and  the  rudiment  of  a  fifth. 

These  and  such  like  revelations  have  come  to  light  in 
our  own  time;  are,  indeed,  still  being  disclosed.  Need- 
less to  say,  no  Index  of  any  sort  now  attempts  to  con- 
ceal them;  yet  something  has  been  accomplished  towards 
the  same  end  by  the  publication  of  the  discoveries  in 
Smithsonian  bulletins,  and  in  technical  memoirs  of 
government  surveys.  Fortunately,  however,  the  results 
have  been  rescued  from  that  partial  oblivion  by  such 
interpreters  as  Professors  Huxley  and  Cope,  so  the  un- 
scientific public  has  been  allowed  to  gain  at  least  an 
inkling  of  the  wonderful  progress  of  paleontology  in  our 
generation. 

The  writings  of  Huxley  in  particular  epitomize  the 

117 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCK 

record.  In  1862  he  admitted  candidly  that  the  paleon- 
tological  record  as  then  known,  so  far  as  it  bears  on  the 
doctrine  of  progressive  development,  negatives  that  doc- 
trine. In  1870  he  was  able  to  "  soften  somewhat  the 
Brutus-like  severity"  of  his  former  verdict,  and  to  assert 
that  the  results  of  recent  researches  seem  "  to  leave  a 
clear  balance  in  favor  of  the  doctrine  of  the  evolution  of 
living  forms  one  from  another."  Six  years  later,  when 
reviewing  the  work  of  Marsh  in  America  and  of  Gaudry 
in  Pikermi,  he  declared  that,  "on  the  evidence  of  paleon- 
tology, the  evolution  of  many  existing  forms  of  animal 
life  from  their  predecessors  is  no  longer  an  hypothesis, 


FOOTPRINTS  OP  REPTILES  POUND  IN  CONNECTICUT  SANDSTONE 
In  the  American  Museum  of  Natural  History 

but  an  historical  fact."  In  1881  he  asserted  that  the 
evidence  gathered  in  the  previous  decade  had  been  so 
unequivocal  that,  had  the  transmutation  hypothesis  not 
existed,  "the  paleontologist  would  have  had  to  invent  it." 
Since  then  the  delvers  after  fossils  have  piled  proof 
on  proof  in  bewildering  profusion.  The  fossil  beds  in 

118 


THE   CENTURY'S   PROGRESS   IN   PALEONTOLOGY 

the  "bad  lands"  of  western  America  seem  inexhaustible. 
And  in  the  Connecticut  River  Valley  near  relatives  of 
the  great  reptiles  which  Professor  Marsh  and  others 
have  found  in  such  profusion  in  the  West  left  their 
tracks  on  the  mud  flats — since  turned  to  sandstone;  and 
a  few  skeletons  also  have  been  found.  The  bodies  of  a 
race  of  great  reptiles  that  were  the  lords  of  creation  of 
their  day  have  been  dissipated  to  their  elements,  while 
the  chance  indentations  of  their  feet  as  they  raced  along 
the  shores,  mere  footprints  on  the  sands,  have  been  pre- 
served among  the  most  imperishable  of  the  memory- 
tablets  of  the  world. 

Of  the  other  vertebrate  fossils  that  have  been  found 
in  the  eastern  portions  of  America,  among  the  most 
abundant  and  interesting  are  the  skeletons  of  masto- 
dons. Of  these  one  of  the  largest  and  most  complete  is 
that  which  was  unearthed  in  the  bed  of  a  drained  lake 
near  Newburg,  New  York,  in  1845.  This  specimen  was 
larger  than  the  existing  elephants,  and  had  tusks  eleven 
feet  in  length.  It  was  mounted  and  described  by  Dr. 
John  C.  Warren,  of  Boston,  and  has  been  famous  for 
half  a  century  as  the  "  Warren  mastodon." 

But  to  the  student  of  racial  development  as  recorded 
by  the  fossils,  all  these  sporadic  finds  have  but  incidental 
interest  as  compared  with  the  rich  Western  fossil  beds 
to  which  we  have  already  referred.  From  records  here 
unearthed  the  racial  evolution  of  many  mammals  has  in 
the  past  few  years  been  made  out  in  greater  or  less 
detail.  Professor  Cope  has  traced  the  ancestry  of  the 
camels  (which,  like  the  rhinoceroses,  hippopotami,  and 
sundry  other  forms  now  spoken  of  as  "  Old  World," 
seem  to  have  had  their  origin  here)  with  much  com- 
pleteness. 

119 


THE   STORY  OF   NINETEENTH-CENTURY  SCIENCE 

A  lemuroid  form  of  mammal,  believed  to  be  of  the 
type  from  which  man  has  descended,  has  also  been  found 
in  these  beds.  It  is  thought  that  the  descendants  of  this 
creature,  and  of  the  other  "Old -World"  forms  above 
referred  to,  found  their  way  to  Asia,  probably,  as  sug- 


TITANOTHERE    FROM     SOUTH    DAKOTA 
In  the  American  Museum  of  Natural  History 

gested  by  Professor  Marsh,  across  a  bridge  at  Bering 
Strait,  to  continue  their  evolution  on  the  other  hemi- 
sphere, becoming  extinct  in  the  land  of  their  nativity. 
The  ape-man  fossil  found  in  the  tertiary  strata  of  the 
island  of  Java  two  years  ago  by  the  Dutch  surgeon  Dr. 
Eugene  Dubois,  and  named  Pithecanthropus  erectus,  may 
have  been  a  direct  descendant  of  the  American  tribe  of 
primitive  lemurs,  though  this  is  only  a  conjecture. 

120 


THE   CENTURY'S   PROGRESS   IN   PALEONTOLOGY 

Not  all  the  strange  beasts  which  w-~c:  *3ft  their  re- 
mains in  our  "  bad  lands  "  are  represented  by  living  de- 
scendants. The  titanotheres,  or  brontotherida3,  for  ex- 
ample, a  gigantic  tribe,  offshoots  of  the  same  stock 
which  produced  the  horse  and  rhinoceros,  represented 
the  culmination  of  a  line  of  descent.  They  developed 
rapidly  in  a  geological  sense,  and  flourished  about  the 
middle  of  the  tertiary  period ;  then,  to  use  Agassiz's 
phrase,  "  time  fought  against  them."  The  story  of  their 
evolution  has  been  worked  out  by  Professors  Leidy, 
Marsh,  Cope,  and  H.  F.  Osborne. 

The  very  latest  bit  of  paleontological  evidence  bear- 
ing on  the  question  of  the  introduction  of  species  is  that 
presented  by  Dr.  J.  L.  Wortman  in  connection  with  the 
fossil  lineage  of  the  edentates.  It  was  suggested  by 
Marsh,  in  1877,  that  these  creatures,  whose  modern  rep- 
resentatives are  all  South  American,  originated  in  North 
America  long  before  the  two  continents  had  any  land 
connection.  The  stages  of  degeneration  by  which  these 
animals  gradually  lost  the  enamel  from  their  teeth,  com- 
ing finally  to  the  unique  condition  of  their  modern  de- 
scendants of  the  sloth  tribe,  are  illustrated  by  strikingly 
graded  specimens  now  preserved  in  the  American  Mu- 
seum of  Natural  History,  as  shown  by  Dr.  Wortman. 

All  these  and  a  multitude  of  other  recent  observations 
that  cannot  be  even  outlined  here  tell  the  same  story 
With  one  accord  paleontologists  of  our  time  regard  the 
question  of  the  introduction  of  new  species  as  solved. 
As  Professor  Marsh  has  said,  "  to  doubt  evolution  to- 
day is  to  doubt  science ;  and  science  is  only  another 
name  for  truth." 

Thus  the  third  great  battle  over  the  meaning  of  the 
fossil  records  has  come  to  a  conclusion.  Again  there 

121 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

is  a  truce  to  controversy,  and  it  may  seem  to  the  casual 
observer  that  the  present  stand  of  the  science  of  fossils 
is  final  and  impregnable.  But  does  this  really  mean 
that  a  full  synopsis  of  the  story  of  paleontology  has 
been  told?  Or  do  we  only  await  the  coming  of  the 
twentieth-century  Lamarck  or  Darwin,  who  shall  attack 
the  fortified  knowledge  of  to-day  with  the  batteries  of 
a  new  generalization  \ 


CHAPTER    IV 
THE  CENTURY'S  PROGRESS  IN  GEOLOGY 


JAMES  BUTTON'S  theory  that  continents  wear  away 
and  are  replaced  by  volcanic  upheaval  had  gained  com- 
paratively few  adherents  at  the  beginning  of  our  cen- 
tury. Even  the  lucid  Illustrations  of  the  Huttonian 
Theory,  which  Playfair,  the  pupil  and  friend  of  the 
great  Scotchman,  published  in  1802,  did  not  at  once 
prove  convincing.  The  world  had  become  enamoured 
of  the  rival  theory  of  Button's  famous  contemporary, 
Werner  of  Saxony — the  theory  which  taught  that  "  in 
the  beginning"  all  the  solids  of  the  earth's  present 
crust  were  dissolved  in  the  heated  waters  of  a  universal 
sea.  Werner  affirmed  that  all  rocks,  of  whatever  char- 
acter, had  been  formed  by  precipitation  from  this  sea,, 
as  the  waters  cooled ;  that  even  veins  have  originated 
in  this  way ;  and  that  mountains  are  gigantic  crystals, 
not  upheaved  masses.  In  a  word,  he  practically  ignored 
volcanic  action,  and  denied  in  toto  the  theory  of  meta- 
morphosis of  rocks  through  the  agency  of  heat. 

The  followers  of  Werner  came  to  be  known  as  Xep- 
tunists;  the  Huttonians  as  Plutonists.  The  history  of 
geology  during  our  first  quarter-century  is  mainly  a  re- 
cital of  the  intemperate  controversy  between  these  op- 

123 


THE   STORY  OF   NINETEENTH-CENTURY   SCIENCE 

posing  schools;  though  it  should  not  be  forgotten  that, 
meantime,  the  members  of  the  Geological  Society  of 
London  were  making  an  effort  to  hunt  for  facts  and 
avoid  compromising  theories.  Fact  and  theory,  how- 
ever, were  too  closely  linked  to  be  thus  divorced. 

The  brunt  of  the  controversy  settled  about  the  un- 
stratified  rocks — granites  and  their  allies — which  the 
Plutonists  claimed  as  of  igneous  origin.  This  contention 
had  the  theoretical  support  of  the  nebular  hypothesis, 
then  gaining  ground,  which  supposed  the  earth  to  be  a 
cooling  globe.  The  Plutonists  laid  great  stress,  too,  on 
the  observed  fact  that  the  temperature  of  the  earth  in- 
creases at  a  pretty  constant  ratio  as  descent  towards  its 
centre  is  made  in  mines.  But  in  particular  they  ap- 
pealed to  the  phenomena  of  volcanoes. 

The  evidence  from  this  source  was  gathered  and 
elaborated  by  Mr.  G.  Poulett  Scrope,  secretary  of  the 
Geological  Society  of  England,  who,  in  1823,  published 
a  classical  work  on  volcanoes,  in  which  he  claimed  that 
volcanic  mountains,  including  some  of  the  highest 
known  peaks,  are  merely  accumulated  masses  of  lava 
belched  forth  from  a  crevice  in  the  earth's  crust.  The 
ISTeptunists  stoutly  contended  for  the  aqueous  origin  of 
volcanic  as  of  other  mountains. 

But  the  facts  were  with  Scrope,  and  as  time  went  on  it 
came  to  be  admitted  that  not  merely  volcanoes,  but  many 
"  trap  "  formations  not  taking  the  form  of  craters  had 
been  made  by  the  obtrusion  of  molten  rock  through  fis- 
sures in  overlying  strata.  Such,  for  example,  to  cite 
familiar  illustrations,  are  Mount  Holyoke,  in  Massachu- 
setts, and  the  well-known  formation  of  the  Palisades 
along  the  Hudson. 

But  to  admit  the  " Plutonic"  origin  of  such  wide- 

124 


THE   CENTURY'S   PROGRESS   IN  GEOLOGY 

spread  formations  was  practically  to  abandon  the  Nep- 
tunian hypothesis.  So  gradually  the  Huttonian  expla- 
nation of  the  origin  of  granites  and  other  "  igneous  "  rocks, 
whether  massed  or  in  veins,  came  to  be  accepted.  Most 
geologists  then  came  to  think  of  the  earth  as  a  molten 
mass,  on  which  the  crust  rests  as  a  mere  film.  Some, 
indeed,  with  Lyell,  preferred  to  believe  that  the  molten 
areas  exist  only  as  lakes  in  a  solid  crust,  heated  to 
melting,  perhaps,  by  electrical  or  chemical  action,  as 
Davy  suggested.  More  recently  a  popular  theory  at- 
tempts to  reconcile  geological  facts  with  the  claim  of  the 
physicists,  that  the  earth's  entire  mass  is  at  least  as 
rigid  as  steel,  by  supposing  that  a  molten  film  rests  be- 
tween the  observed  solid  crust  and  the  alleged  solid 
nucleus.  But  be  that  as  it  may,  the  theory  that  subter- 
ranean heat  has  been  instrumental  in  determining  the 
condition  of  "  primary  "  rocks,  and  in  producing  many 
other  phenomena  of  the  earth's  crust,  has  never  been  in 
dispute  since  the  long  controversy  between  the  Neptu- 
nists  and  the  Plutonists  led  to  its  establishment. 


ii 

If  molten  matter  exists  beneath  the  crust  of  the  earth, 
it  must  contract  an  cooling,  and  in  so  doing  it  must  dis- 
turb the  level  of  the  portion  of  the  crust  already  solidi- 
fied. So  a  plausible  explanation  of  the  upheaval  of 
continents  and  mountains  was  supplied  by  the  Plutonian 
theory,  as  Hutton  had  from  the  first  alleged.  But 
now  an  important  difference  of  opinion  arose  as  to  the 
exact  rationale  of  such  upheavals.  Hutton  himself,  and 
practically  every  one  else  who  accepted  his  theory,  had 
supposed  that  there  are  long  periods  of  relative  repose, 

125 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

during  which  the  level  of  the  crust  is  undisturbed,  fol- 
lowed by  short  periods  of  active  stress,  when  continents 
are  thrown  up  with  volcanic  suddenness,  as  by  the  throes 
of  a  gigantic  earthquake.  But  now  came  Charles  Lyell 
with  his  famous  extension  of  the  "  uniformitarian  "  doc- 
trine, claiming  that  past  changes  of  the  earth's  surface 
have  been  like  present  changes  in  degree  as  well  as  in 
kind.  The  making  of  continents  and  mountains,  he  said, 
is  going  on  as  rapidly  to-day  as  at  any  time  in  the  past. 
There  have  been  no  gigantic  cataclysmic  upheavals  at  any 
time,  but  all  changes  in  level  of  the  strata  as  a  whole  have 
been  gradual,  by  slow  oscillation,  or  at  most  by  repeated 
earthquake  shocks  such  as  are  still  often  experienced. 

In  support  of  this  very  startling  contention  Lyell 
gathered  a  mass  of  evidence  of  the  recent  changes  in 
level  of  continental  areas.  He  corroborated  by  personal 
inspection  the  claim  which  had  been  made  by  Play  fair 
in  1802,  and  by  von  Buch  in  1807,  that  the  coast-line  of 
Sweden  is  rising  at  the  rate  of  from  a  few  inches  to  sev- 
eral feet  in  a  century.  He  cited  Darwin's  observations 
going  to  prove  that  Patagonia  is  similarly  rising,  and 
PingeL's  claim  that  Greenland  is  slowly  sinking.  Proof 
as  to  sudden  changes  of  level  of  several  feet,  over  large 
areas,  due  to  earthquakes,  was  brought  forward  in 
abundance.  Cumulative  evidence  left  it  no  longer  open 
to  question  that  such  oscillatory  changes  of  level,  either 
upward  or  downward,  are  quite  the  rule,  and  it  could 
not  be  denied  that  these  observed  changes,  if  continued 
long  enough  in  one  direction,  would  produce  the  highest 
elevations.  The  possibility  that  the  making  of  even  the 
highest  ranges  of  mountains  had  been  accomplished 
without  exaggerated  catastrophic  action  came  to  be 
freely  admitted. 

126 


THE   RESULTS  OF   EROSION   BY  RUNNING   WATER 


TI1E   CENTURY'S   PROGRESS   IN   GEOLOGY 

It  became  clear  that  the  supposedly  stable  land  sur- 
faces are  in  reality  much  more  variable  than  the  surface 
of  the  "shifting sea"  ;  that  continental  masses,  seeming- 
ly so  fixed,  are  really  rising  and  falling  in  billows  thou- 
sands of  feet  in  height,  ages  instead  of  moments  being 
consumed  in  the  sweep  between  crest  and  hollow. 

These  slow  oscillations  of  land  surfaces  being  under- 
stood, many  geological  enigmas  were  made  clear — such 
as  the  alternation  of  marine  and  fresh-water  formations 
in  a  vertical  series,  which  Cuvier  and  Brongniart  had 
observed  near  Paris;  or  the  sandwiching  of  layers  of 
coal,  of  subaerial  formation,  between  layers  of  subaque- 
ous clay  or  sandstone,  which  may  be  observed  every- 
where in  the  coal  measures.  In  particular,  the  extreme 
thickness  of  the  sedimentary  strata  as  a  whole,  many 
times  exceeding  the  depth  of  the  deepest  known  sea, 
was  for  the  first  time  explicable  when  it  was  under- 
stood that  such  strata  had  formed  in  slowly  sinking 
ocean-beds. 

All  doubt  as  to  the  mode  of  origin  of  stratified  rocks 
being  thus  removed,  the  way  was  opened  for  a  more 
favorable  consideration  of  that  other  Huttonian  doc- 
trine of  the  extremely  slow  denudation  of  land  surfaces. 
The  enormous  amount  of  land  erosion  will  be  patent  to 
any  one  who  uses  his  eyes  intelligently  in  a  mountain 
district.  It  will  be  evident  in  any  region  where  the 
strata  are  tilted — as,  for  example,  the  Alleghanies— 
that  great  folds  of  strata  which  must  once  have  risen 
miles  in  height  have  in  many  cases  been  worn  entirely 
away,  so  that  now  a  valley  marks  the  location  of  the 
former  eminence.  Where  the  strata  are  level,  as  in  the 
case  of  the  mountains  of  Sicily,  the  Scotch  Highlands, 
and  the  familiar  Catskills,  the  evidence  of  denudation  is, 
i  129 


T1IE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

if  possible,  even  more  marked ;  for  here  it  is  clear  that 
elevation  and  valley  have  been  carved  by  the  elements 
out  of  land  that  rose  from  the  sea  as  level  plateaus. 

But  that  this  herculean  labor  of  land-sculpturing  could 
have  been  accomplished  by  the  slow  action  of  wind  and 
frost  and  shower  was  an  idea  few  men  could  grasp 
within  the  first  half-century  after  Hutton  propounded 
it;  nor  did  it  begin  to  gain  general  currency  until 
Lyell's  crusade  against  catastrophism,  begun  about  1830, 
had  for  a  quarter  of  a  century  accustomed  geologists  to 
the  thought  of  slow  continuous  changes  producing  final 
results  of  colossal  proportions.  And  even  long  after 
that,  it  was  combated  by  such  men  as  Murchison,  Di- 
rector-General of  the  Geological  Survey  of  Great  Brit- 
ain, then  accounted  the  foremost  field-geologist  of  his 
time,  who  continued  to  believe  that  the  existing  valleys 
owe  their  main  features  to  subterranean  forces  of  up- 
heaval. Even  Murchison,  however,  made  some  recession 
from  the  belief  of  the  Continental  authorities,  Elie  de 
Beaumont  and  Leopold  von  Buch,  who  contended  that 
the  mountains  had  sprung  up  like  veritable  jacks-in-the- 
box.  Yon  Buch,  whom  his  friend  and  fellow-pupil  von 
Humboldt  considered  the  foremost  geologist  of  the  time, 
died  in  1853,  still  firm  in  his  early  faith  that  the  erratic 
bowlders  found  high  on  the  Jura  had  been  hurled  there, 
like  cannon-balls,  across  the  valley  of  Geneva  by  the 
sudden  upheaval  of  a  neighboring  mountain  range. 


in 

The  bowlders  whose  presence  on  the  crags  of  the  Jura 
the  old  German  accounted  for  in  a  manner  so  theatrical 
had  long  been  a  source  of  contention  among  geologists. 

130    • 


THE  CENTURY'S  PROGRESS  IN  GEOLOGY 

They  are  found  not  merely  on  the  Jura,  but  on  number- 
less other  mountains  in  all  north  temperate  latitudes, 
and  often  far  out  in  the  open  country,  as  many  a  farmer 
who  has  broken  his  plough  against  them  might  testify. 
The  early  geologists  accounted  for  them,  as  for  nearly 
everything  else,  with  their  supposititious  Deluge.  Brong- 


THE  RESULTS  OF  EROSION  BY  WIND 

niartand  Cuvierand  Buckland  and  their  contemporaries 
appeared  to  have  no  difficulty  in  conceiving  that  masses 
of  granite  weighing  hundreds  of  tons  had  been  swept 
by  this  current  scores  or  hundreds  of  miles  from  their 
source.  But  of  course  the  uniformitarian  faith  permit- 
ted no  such  explanation,  nor  could  it  countenance  the 
projection  idea;  so  Lyell  was  bound  to  find  some  other 
means  of  transportation  for  the  puzzling  erratics. 
The  only  available  medium  was  ice,  but  fortunately 

131 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

this  one  seemed  quite  sufficient.  Icebergs,  said  Lyell, 
are  observed  to  cany  all  manner  of  debris,  and  deposit 
it  in  the  sea-bottoms.  Present  land  surfaces  have  often 
been  submerged  beneath  the  sea.  During  the  latest  of 
these  submergences  icebergs  deposited  the  bowlders  now 
scattered  here  and  there  over  the  land.  Nothing  could 
be  simpler  or  more  clearly  uniformitarian.  And  even 
the  catastrophists,  though  they  met  Lyell  amicably  on 
almost  no  other  theoretical  ground,  were  inclined  to  ad- 
mit the  plausibility  of  his  theory  of  erratics.  Indeed,  of 
all  Ly  ell's  non-conformist  doctrines,  this  seemed  the  one 
most  likely  to  meet  with  general  acceptance. 

Yet,  even  as  this  iceberg  theory  loomed  large  and 
larger  before  the  geological  world,  observations  were 
making  in  a  different  field  that  were  destined  to  sjiow 
its  fallacy.  As  early  as  1815  a  sharp-eyed  chamois-hunt- 
er of  the  Alps,  Perraudin  by  name,  had  noted  the  ex- 
istence of  the  erratics,  and,  unlike  most  of  his  companion 
hunters,  had  puzzled  his  head  as  to  how  the  bowlders 
got  where  he  saw  them.  He  knew  nothing  of  sub- 
merged continents  or  of  icebergs,  still  less  of  upheaving 
mountains;  and  though  he  doubtless  had  heard  of  the 
Flood,  he  had  no  experience  of  heavy  rocks  Hoating  like 
corks  in  water.  Moreover,  he  had  never  observed  stones 
rolling  up  hill  and  perching  themselves  on  mountain- 
tops,  and  he  was  a  good  enough  uniformitarian  (though 
he  would  have  been  puzzled  indeed  had  any  one  told 
him  so)  to  disbelieve  that  stones  in  past  times  had  dis- 
ported themselves  differently  in  this  regard  from  stones 
of  the  present.  Yet  there  the  stones  are.  How  did  they 
get  there? 

The  mountaineer  thought  that  he  could  answer  that 
question.  He  saw  about  him  those  gigantic  serpent-like 

132 


THE   CENTURY'S   PROGRESS   IN   GEOLOGY 

streams  of  ice  called  glaciers,  "  from  their  far  fountains 
slow  rolling  on,"  carrying  with,  them  blocks  of  granite 
and  other  debris  to  form  moraine  deposits.  If  these 
glaciers  had  once  been  much  more  extensive  than  they 
now  are,  they  might  have  carried  the  bowlders  and  left 
them  where  we  find  them.  On  the  other  hand,  no  other 
natural  agency  within  the  sphere  of  the  chamois-hunt- 


A  MOUNTAIN   CARVED  FROM  HORIZONTAL  STRATA 

er's  knowledge  could  have  accomplished  this,  ergo  the 
glaciers  must  once  have  been  more  extensive.  Perraudin 
would  probably  have  said  that  common-sense  drove  him 
to  this  conclusion  ;  but  be  that  as  it  may,  he  had  con- 
ceived one  of  the  few  truly  original  and  novel  ideas  of 
which  our  century  can  boast. 

133 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

Perraudin  announced  his  idea  to  the  greatest  scientist 
in  his  little  world— Jean  de  Charpentier,  director  of  the 
mines  at  Bex,  a  skilled  geologist  who  had  been  a  fellow- 
pupil  of  von  Buch  and  von  Humboldt  under  Werner  at 
the  Freiberg  School  of  Mines.  Charpentier  laughed  at 
the  mountaineer's  grotesque  idea,  and  thought  no  more 
about  it.  And  ten  years  elapsed  before  Perraudin  could 
find  any  one  who  treated  his  notion  with  greater  re- 
spect. Then  he  found  a  listener  in  M.  Yenetz,  a  civil 
engineer,  who  read  a  paper  on  the  novel  glacial  theory 
before  a  local  society  in  1823.  This  brought  the  matter 
once  more  to  the  attention  of  de  Charpentier,  who  now 
felt  that  there  might  be  something  in  it  worth  investi- 
gation. 

A  survey  of  the  field  in  the  light  of  the  new  theory 
soon  convinced  Charpentier  that  the  chamois-hunter  had 
all  along  been  right.  He  became  an  enthusiastic  sup- 
porter of  the  idea  that  the  Alps  had  once  been  embed- 
ded in  a  mass  of  ice,  and  in  1836  he  brought  the  notion 
to  the  attention  of  Louis  Agassiz,  who  was  spending  the 
summer  in  the  Alps.  Agassiz  was  sceptical  at  first,  but 
soon  became  a  convert.  Then  he  saw  that  the  implica- 
tions of  the  theory  extended  far  beyond  the  Alps.  If 
the  Alps  had  been  covered  with  an  ice  sheet,  so  had 
many  other  regions  of  the  northern  hemisphere.  Cast- 
ing abroad  for  evidences  of  glacial  action,  Agassiz  found 
them  everywhere,  in  the  form  of  transported  erratics, 
scratched  and  polished  outcropping  rocks,  and  moraine- 
like  deposits.  Presently  he  became  convinced  that  the 
ice  sheet  which  covered  the  Alps  had  spread  over  the 
whole  of  the  higher  latitudes  of  the  northern  hemi- 
sphere, forming  an  ice  cap  over  the  globe.  Thus  the 
common -sense  induction  of  the  chamois -hunter  blos- 

134 


THE  CENTURY'S  PROGRESS  IN  GEOLOGY 


LOUIS  JEAN  RODOLPH   AGASSIZ 


somed  in  the  mind  of  Ag- 
assiz into  the  conception 
of  a  universal  Ice  Age. 

In  1857  Agassiz  intro- 
duced his  theory  to  the 
world,  in  a  paper  read 
at  Neuchatel,  and  three 
years  later  he  published 
his  famous  Etudes  sur  les 
Glaciers.  Never  did  idea 
make  a  more  profound 
disturbance  in  the  scien- 
tilic  world.  Yon  Buch 
treated  it  with  alternate 
ridicule,  contempt,  and 
rage;  Murchi'son  opposed  it  with  customary  vigor;  even 
Lyell,  whose  most  remarkable  mental  endowment  was 
an  unfailing  receptiveness  to  new  truths,  could  not  at 

once  discard  his  ice- 
berg theory  in  favor  of 
the  new  claimant.  Dr. 
Buckland,  however,  af- 
ter Agassiz  had  shown 
him  evidence  of  for- 
mer glacial  action  in 
his  own  Scotland,  be- 
came a  convert  —  the 
more  readily,  perhaps, 
as  it  seemed  to  him  to 
oppose  the  uniformita- 
rian  idea.  Gradually 
others  fell  in  line,  and 
after  the  usual  embit- 


ADAH   SEDGWICK,   P.R.S. 


135 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

tered  controversy  and  the  inevitable  full  generation  of 
probation,  the  idea  of  an  Ice  Age  took  its  place  among 
the  accepted  tenets  of  geology.  All  manner  of  moot 
points  still  demanded  attention  —  the  cause  of  the  Ice 
Age,  the  exact  extent  of  the  ice  sheet,  the  precise 
manner  in  which  it  produced  its  effects,  and  the  exact 
nature  of  these  effects  ;  and  not  all  of  these  have  even 
yet  been  determined.  But,  details  aside,  the  Ice  Age 
now  has  full  recognition  from  geologists  as  an  historical 
period.  There  may  have  been  many  Ice  Ages,  as  Dr. 
Croll  contends;  there  was  surely  one;  and  the  concep- 
tion of  such  a  period  is  one  of  the  very  few  ideas  of  our 
century  that  no  previous  century  had  even  so  much  as 
faintly  adumbrated. 

IV 

But,  for  that  matter,  the  entire  subject  of  historical 
geology  is  one  that  had  but  the  barest  beginning  before 
our  century.  Until  the  paleontologist  found  out  the 
key  to  the  earth's  chronology,  no  one— not  even  Hutton 
— could  have  any  definite  idea  as  to  the  true  story  of  the 
earth's  past.  The  only  conspicuous  attempt  to  classify 
the  strata  was  that  made  by  Werner,  who  divided  the 
rocks  into  three  systems,  based  on  their  supposed  order 
of  deposition,  and  called  primary,  transition,  and  sec- 
ondary. 

Though  Werner's  observations  were  confined  to  the 
small  province  of  Saxony,  he  did  not  hesitate  to  affirm 
that  all  over  the  world  the  succession  of  strata  would  be 
found  the  same  as  there,  the  concentric  layers,  accord- 
ing to  this  conception,  being  arranged  about  the  earth 
with  the  regularity  of  layers  on  an  onion.  But  in  this 
Werner  was  as  mistaken  as  in  his  theoretical  explana- 

136 


THE  CENTURY'S  PROGRESS  IN  GEOLOGY 


JAMES   DWIGHT  DANA 


tion  of  the  origin  of  the 
"  primary  "  rocks.  It  re- 
quired but  little  observa- 
tion to  show  that  the  ex- 
act succession  of  strata 
is  never  precisely  the 
same  in  any  widely  sep- 
arated regions.  Never- 
theless, there  was  a  germ 
of  truth  in  Werner's  sys- 
tem. It  contained  the 
idea,  however  faultily  in- 
terpreted, of  a  chronolog- 
ical succession  of  strata ; 
and  it  furnished  a  work- 
ing outline  for  the  observers  who  were  to  make  out  the 
true  story  of  geological  development.  But  the  correct 
interpretation  of  the  observed  facts  could  only  be  made 

after  the  Huttonian  view 
as  to  the  origin  of  strata 
had  gained  complete  ac- 
ceptance. 

When  William  Smith, 
having  found  the  true  key 
to  this  story,  attempted 
to  apply  it,  the  territory 
with  which  he  had  to 
deal  chanced  to  be  one 
where  the  surface  rocks 
are  of  that  later  series 
which  Werner  termed  sec- 
ondary. He  made  numer- 
rous  subdivisions  within 
137 


SIR  RODERICK   IMPEY  MURCHISON 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

this  system,  based  mainly  on  the  fossils.  Meantime  it 
was  found  that,  judged  by  the  fossils,  the  strata  that 
Brongniart  and  Cuvier  studied  near  Paris  were  of  a  still 
more  recent  period  (presumed  at  first  to  be  due  to  the 
latest  deluge),  which  came  to  be  spoken  of  as  tertiary. 
It  was  in  these  beds,  some  of  which  seemed  to  have  been 
formed  in  fresh- water  lakes,  that  many  of  the  strange 
mammals  which  Cuvier  first  described  were  found. 

But  the  "  transition  "  rocks,  underlying  the  "  second- 
ary "  system  that  Smith  studied,  were  still  practically 
unexplored  when,  along  in  the  thirties,  they  were  taken 
in  hand  by  Roderick  Impey  Murchison,  the  reformed 
fox-hunter  and  ex-captain  who  had  turned  geologist  to 
such  notable  advantage,  and  Adam  Sedgwick,  the  brill- 
iant Woodwardian  professor  at  Cambridge. 

Working  together,  these  two  friends  classified  the 
transition  rocks  into  chronological  groups,  since  familiar 
to  every  one  in  the  larger  outlines  as  the  Silurian  system 
(age  of  invertebrates)  and  the  Devonian  system  (age  of 
fishes)— names  derived  respectively  from  the  country  of 
the  ancient  Silures,  in  Wales,  and  Devonshire,  England. 
It  was  subsequently  discovered  that  these  systems  of 
strata,  which  crop  out  from  beneath  newer  rocks  in  re- 
stricted areas  in  Britain,  are  spread  out  into  broad  un- 
disturbed sheets  over  thousands  of  miles  in  continental 
Europe  and  in  America.  Later  on  Murchison  studied 
them  in  Russia,  and  described  them,  conjointly  with 
Verneuil  and  von  Kerserling,  in  a  ponderous  and  classi- 
cal work.  In  America  they  were  studied  by  Hall,  New- 
berry,  Whitney,  Dana,  Whitfield,  and  other  pioneer 
geologists,  who  all  but  anticipated  their  English  contem- 
poraries. 

The  rocks  that  are  of  still  older  formation  than  those 

138 


THE   CENTURY'S   PROGRESS   IN   GEOLOGY 

studied  by  Murchison  and  Sedgwick  (corresponding  in 
location  to  the  "  primary  "  rocks  of  Werner's  concep- 
tion) are  the  surface  feature  of  vast  areas  in  Canada, 
and  were  first  prominently  studied  there  by  William  I. 


WILLIAM   SMITH,   LL.D. 


Logan,  of  the  Canadian  Government  Survey,  as  early  as 
1846,  and  later  on  by  Sir  William  Dawson.  These  rocks 
— comprising  theLaurentian  system — were  formerly  sup- 
posed to  represent  parts  of  the  original  crust  of  the  earth, 

139 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

formed  on  first  cooling  from  a  molten  state ;  but  they 
are  now  more  generally  regarded  as  once-stratified  de- 
posits metamorphosed  by  the  action  of  heat. 

Whether  "  primitive  "  or  metamorphic,  however,  these 
Canadian  rocks,  and  analogous  ones  beneath  the  fossil- 
iferous  strata  of  other  countries,  are  the  oldest  portions 
of  the  earth's  crust  of  which  geology  has  any  present 
knowledge.  Mountains  of  this  formation,  as  the  Adi- 
rondacks,  and  the  Storm  King  range  overlooking  the 
Hudson  near  West  Point,  are  the  patriarchs  of  their 
kind,  beside  which  Alleghanies  and  Sierra  Nevadas  are 
recent  upstarts,  and  Rockies,  Alps,  and  Andes  are  mere 
parvenus  of  yesterday. 

The  Laurentian  rocks  were  at  first  spoken  of  as  repre- 
senting "Azoic"  time;  but  in  1846  Dawson  found  a 
formation  deep  in  their  midst  which  was  believed  to  be 
the  fossil  relic  of  a  very  low  form  of  life,  and  after  that 
it  became  customary  to  speak  of  the  system  as  "  Eozoic." 
Still  more  recently  the  title  of  Dawson's  supposed  fossil 
to  rank  as  such  has  been  questioned,  and  Dana's  sug- 
gestion that  the  early  rocks  be  termed  merely  Archaean 
has  met  with  general  favor.  Murchison  and  Sedgwick's 
Silurian,  Devonian,  and  Carboniferous  groups  (the  ages 
of  invertebrates,  of  fishes,  and  of  coal  plants  respective- 
ly) are  together  spoken  of  as  representing  Paleozoic  time. 
William  Smith's  system  of  strata,  next  above  these,  once 
called  "  secondary,"  represents  Mesozoic  time,  or  the  age 
of  reptiles.  Still  higher,  or  more  recent,  are  Cuvier 
and  Brongniart's  Tertiary  rocks,  representing  the  age  of 
mammals.  Lastly,  the  most  recent  formations,  dating 
back,  however,  to  a  period  far  enough  from  recent  in 
any  but  a  geological  sense,  are  classed  as  Quaternary, 
representing  the  age  of  man. 

140 


THE   CENTURY'S   PROGRESS   IN   GEOLOGY 


It  must  not  be  sup- 
posed, however,  that 
the  successive  "ages" 
of  the  geologist  are 
shut  off  from  one  an- 
other in  any  such  ar- 
bitrary way -as  this  ver- 
bal classification  might 
seem  to  suggest.  In 
point  of  fact,  these 
"  ages  "  have  no  better 
warrant  for  existence 
than  have  the  "cen- 
turies" and  the  "weeks" 

of    e Very-day    COlXlputa-  GEORGE  POULETTE  SCROPE,  P.E.a 

tion.  They  are  convenient,  and  they  may  even  stand 
for  local  divisions  in  the  strata,  but  they  are  bounded  by 
no  actual  gaps  in  the  sweep  of  terrestrial  events. 

Moreover,  it  must  be 
understood  that  the 
"  ages "  of  different 
continents,  though  de- 
scribed under  the  same 
name,  are  not  neces- 
sarily of  exact  contem- 
poraneity. There  is  no 
sure  test  available  by 
which  it  could  be 
shown  that  the  Devo- 
nian age,  for  instance, 
as  outlined  in  the 
strata  of  Europe,  did 
not  begin  millions  of 


SIB  CHARLES  LYELL,  BART,  F.R.S. 


141 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

years  earlier  or  later  than  the  period  whose  records  are 
said  to  represent  the  Devonian  age  in  America.  In  at- 
tempting to  decide  such  details  as  this,  mineralogical 
data  fail  us  utterly.  Even  in  rocks  of  adjoining  regions 
identity  of  structure  is  no  proof  of  contemporaneous 
origin ;  for  the  veritable  substance  of  the  rock  of  one 
age  is  ground  up  to  build  the  rocks  of  subsequent  ages. 
Furthermore,  in  seas  where  conditions  change  but  little 
the  same  form  of  rock  may  be  made  age  after  age.  It 
is  believed  that  chalk  beds  still  forming  in  some  of  our 
present  seas  may  form  one  continuous  mass  dating  back 
to  earliest  geologic  ages.  On  the  other  hand,  rocks  dif- 
ferent in  character  may  be  formed  at  the  same  time  in 
regions  not  far  apart — say  a  sandstone  along  shore,  a 
coral  limestone  farther  seaward,  and  a  chalk  bed  be- 
yond. This  continuous  stratum,  broken  in  the  process 
of  upheaval,  might  seem  the  record  of  three  different 
epochs. 

Paleontology,  of  course,  supplies  far  better  chrono- 
logical tests,  but  even  these  have  their  limitations. 
There  has  been  no  time  since  rocks  now  in  existence 
were  formed,  if  ever,  when  the  earth  had  a  uniform 
climate  and  a  single  undi versified  fauna  over  its  entire 
land  surface,  as  the  early  paleontologists  supposed. 
Speaking  broadly,  the  same  general  stages  have  attend- 
ed the  evolution  of  organic  forms  everywhere,  but  there 
is  nothing  to  show  that  equal  periods  of  time  witnessed 
corresponding  changes  in  diverse  regions,  but  quite  the 
contrary.  To  cite  but  a  single  illustration,  the  marsupial 
order,  which  is  the  dominant  mammalian  type  of  the 
living  fauna  of  Australia  to-day,  existed  in  Europe  and 
died  out  there  in  the  Tertiary  age.  Hence  a  future 
geologist  might  think  the  Australia  of  to-day  contempo- 

142 


OK    THK 

UNIVERSITY 


THE  CENTURY'S   PROGRESS   IN   GEOLOGY 

raneous  with  a  period  in  Europe  which  in  reality  ante- 
dated it  by  perhaps  millions  of  year 


v 

All  these  puzzling  features  unite  to  render  the  subject 
of  historical  geology  anything  but  the  simple  matter  the 
fathers  of  the  science  esteemed  it.  No  one  would  now 
attempt  to  trace  the  exact  sequence  of  formation  of  all 
the  mountains  of  the  globe,  as  Elie  de  Beaumont  did  a 
half-century  ago.  Even  within  the  limits  of  a  single 
continent,  the  geologist  must  proceed  with  much  caution 
in  attempting  to  chronicle  the  order  in  which  its  various 
parts  rose  from  the  matrix  of  the  sea.  The  key  to  this 
story  is  found  in  the  identification  of  the  strata  that  are 
the  surface  feature  in  each  territory.  If  Devonian  rocks 
are  at  the  surface  in  any  given  region,  for  example,  it 
would  appear  that  this  region  became  a  land  surface  in 
the  Devonian  age,  or  just  afterwards.  But  a  moment's 
consideration  shows  that  there  is  an  element  of  uncer- 
tainty about  this,  due  to  the  steady  denudation  that  all 
land  surfaces  undergo.  The  Devonian  rocks  may  lie  at 
the  surface  simply  because  the  thousands  of  feet  of  car- 
boniferous strata  that  once  lay  above  them  have  been 
worn  away.  All  that  the  cautious  geologist  dare  assert, 
therefore,  is  that  the  region  in  question  did  not  become 
permanent  land  surface  earlier  than  the  Devonian  age. 

But  to  know  even  this  is  much — sufficient,  indeed,  to 
establish  the  chronological  order  of  elevation,  if  not  its 
exact  period,  for  all  parts  of  any  continent  that  have 
been  geologically  explored — understanding  always  that 
there  must  be  no  scrupling  about  a  latitude  of  a  few  mill- 
ions  or  perhaps  tens  of  millions  of  years  here  and  there. 
K  145 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

Regarding  our  own  continent,  for  example,  we  learn 
through  the  researches  of  a  multitude  of  workers  that 
in  the  early  day  it  was  a  mere  archipelago.  Its  chief 
island — the  backbone  of  the  future  continent — was  a 
great  Y-  shaped  area  surrounding  what  is  now  Hudson 
Bay,  an  area  built  up,  perhaps,  through  denudation  of  a 
yet  more  ancient  polar  continent,  whose  existence  is  only 
conjectured.  To  the  southeast  an  island  that  is  now  t-he 
Adirondack  Mountains,  and  another  that  is  now  the 
Jersey  Highlands,  rose  above  the  waste  of  waters ;  and 
far  to  the  south  stretched  probably  a  line  of  islands  now 
represented  by  the  Blue  Ridge  Mountains.  Far  off  to 
the  westward  another  line  of  islands  foreshadowed  our 
present  Pacific  border.  A  few  minor  islands  in  the  in- 
terior completed  the  archipelago. 

From  this  bare  skeleton  the  continent  grew,  partly  by 
the  deposit  of  sediment  from  the  denudation  of  the  orig- 
inal islands  (which  once  towered  miles,  perhaps,  where 
now  they  rise  thousands  of  feet),  but  largely  also  by  the 
deposit  of  organic  remains,  especially  in  the  interior  sea, 
which  teemed  with  life.  In  the  Silurian  ages,  inverte- 
brates— brachiopods  and  crinoids,and  cephalopoda — were 
the  dominant  types.  But  very  early — no  one  knows  just 
when — there  came  fishes  of  many  strange  forms,  some 
of  the  early  ones  enclosed  in  turtlelike  shells.  Later 
yet,  large  spaces  within  the  interior  sea  having  risen  to 
the  surface,  great  marshes  or  forests  of  strange  types  of 
vegetation  grew  and  deposited  their  remains  to  form 
coal  beds.  Many  times  over  such  forests  were  formed, 
only  to  be  destroyed  by  the  oscillations  of  the  land  sur- 
face. All  told,  the  strata  of  this  Paleozoic  period  aggre- 
gate several  miles  in  thickness,  and  the  time  consumed 
in  their  formation  stands  to  all  later  time  up  to  the 

146 


THE   CENTURY'S   PROGRESS   IN   GEOLOGY 

present,  according  to  Professor  Dana's  estimate,  as  three 
to  one. 

Towards  the  close  of  this  Paleozoic  era  the  Appalachian 
Mountains  were  slowly  upheaved  in  great  convoluted 
folds,  some  of  them  probably  reaching  three  or  four 
miles  above  the  sea-level,  though  the  tooth  of  time  has 
since  gnawed  them  down  to  comparatively  puny  limits. 
The  continental  areas  thus  enlarged  were  peopled  dur- 
ing the  ensuing  Mesozoic  time  with  multitudes  of 
strange  reptiles,  many  of  them  gigantic  in  size.  The 
waters,  too,  still  teeming  with  invertebrates  and  fishes, 
had  their  quota  of  reptilian  monsters;  and  in  the  air 
were  flying  reptiles,  some  of  which  measured  twenty-five 
feet  from  tip  to  tip  of  their  bat-like  wings.  During  this 
era  the  Sierra  Nevada  Mountains  rose.  Near  the  east- 
ern border  of  the  forming  continent  the  strata  were  per- 
haps now  too  thick  and  stiff  to  bend  into  mountain 
folds,  for  they  were  rent  into  great  fissures,  letting  out 
floods  of  molten  lava,  remnants  of  which  are  still  in  evi- 
dence after  ages  of  denudation,  as  the  Palisades  along 
the  Hudson,  and  such  elevations  as  Mount  Holyoke  in 
western  Massachusetts. 

Still  there  remained  a  vast  interior  sea,  which,  later 
on,  in  the  Tertiary  age,  was  to  be  divided  by  the  slow 
uprising  of  the  land,  which  only  yesterday — that  is  to 
say,  a  million,  or  three  or  five  or  ten  million  years  ago— 
became  the  Rocky  Mountains.  High  and  erect  these 
young  mountains  stand  to  this  day,  their  sharp  angles 
and  rocky  contours  vouching  for  their  youth,  in  strange 
contrast  with  the  shrunken  forms  of  the  old  Adiron- 
dacks,  Green  Mountains,  and  Appalachians,  whose  low- 
ered heads  and  rounded  shoulders  attest  the  weight  of 
ages.  In  the  vast  lakes  which  still  remained  on  either 

140 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

side  of  the  Rocky  range,  Tertiary  strata  were  slowly 
formed  to  the  ultimate  depth  of  two  or  three  miles,  en- 
closing here  and  there  those  vertebrate  remains  which 
were  to  be  exposed  again  to  view  by  denudation  when 
the  land  rose  still  higher,  and  then,  in  our  own  time,  to 
tell  so  wonderful  a  story  to  the  paleontologist. 

Finally  the  interior  seas  were  filled,  and  the  shore 
lines  of  the  continent  assumed  nearly  their  present  out- 
line. 

Then  came  the  long  winter  of  the  glacial  epoch — per- 
haps of  a  succession  of  glacial  epochs.  The  ice  sheet 
extended  southward  to  about  the  fortieth  parallel,  driv- 
ing some  animals  before  it,  and  destroying  those  that 
were  unable  to  migrate.  At  its  fulness,  the  great  ice 
mass  lay  almost  a  mile  in  depth  over  New  England,  as 
attested  by  the  scratched  and  polished  rock  surfaces  and 
deposited  erratics  in  the  White  Mountains.  Such  a  mass 
presses  down  with  a  weight  of  about  one  hundred  and 
twenty-five  tons  to  the  square  foot,  according  to  Dr. 
CrolFs  estimate.  It  crushed  and  ground  everything  be- 
neath it  more  or  less,  and  in  some  regions  planed  off 
hilly  surfaces  into  prairies.  Creeping  slowly  forward,  it 
carried  all  manner  of  debris  with  it.  When  it  melted 
away  its  terminal  moraine  built  up  the  nucleus  of  the 
land  masses  now  known  as  Long  Island  and  Staten  Isl- 
and ;  other  of  its  deposits  formed  the  "  drumlins  "  about 
Boston  famous  as  Bunker  and  Breeds  hills;  and  it  left  a 
long  irregular  line  of  ridges  of  "  till "  or  bowlder  clay 
and  scattered  erratics  clear  across  the  country  at  about 
the  latitude  of  New  York  City. 

As  the  ice  sheet  slowly  receded  it  left  minor  moraines 
all  along  its  course.  Sometimes  its  deposits  dammed  up 
river  courses  or  inequalities  in  the  surface,  to  form  the 

150 


*«•     .IHB  'K^S 

UNlVERsiTr 
-Op 


THE   CENTURY'S   PROGRESS   IN   GEOLOGY 

lakes  which  everywhere  abound  over  Northern  territo- 
ries. Some  glacialists  even  hold  the  view  first  suggested 
by  Kamsey,  of  the  British  Geological  Survey,  that  the 
great  glacial  sheet  scooped  out  the  basins  of  many  lakes, 
including  the  system  that  feeds  the  Saint  Lawrence.  At 
all  events,  it  left  traces  of  its  presence  all  along  the  line 
of  its  retreat,  and  its  remnants  exist  to  this  day  as 
mountain  glaciers  and  the  polar  ice  cap.  Indeed,  we 
live  on  the  border  of  the  last  glacial  epoch,  for  with  the 
closing  of  this  period  the  long  geologic  past  merges  into 
the  present. 

VI 

And  the  present,  no  less  than  the  past,  is  a  time  of 
change.  That  is  the  thought  which  James  Hutton  con- 
ceived more  than  a  century  ago,  but  which  his  contem- 
poraries and  successors  were  so  very  slow  to  appreciate. 
Now,  however,  it  has  become  axiomatic— one  can  hardly 
realize  that  it  was  ever  doubted.  Every  new  scientific 
truth,  says  Agassiz,  must  pass  through  three  stages- 
first,  men  say  it  is  not  true  ;  then  they  declare  it  hostile 
to  religion ;  finally,  they  assert  that  every  one  has 
known  it  always.  Hutton's  truth  that  natural  law  is 
changeless  and  eternal  has  reached  this  final  stage.  No- 
where now  could  you  find  a  scientist  who  would  dispute 
the  truth  of  that  text  which  Lyell,  quoting  from  Play- 
fair's  Illustrations  of  the  Huttonian  Theory,  printed  on 
the  title-page  of  his  Principles:  "Amid  all  the  revolu- 
tions of  the  globe  the  economy  of  Nature  has  been  uni- 
form, and  her  laws  are  the  only  things  that  have  resisted 
the  general  movement.  The  rivers  and  the  rocks,  the 
seas  and  the  continents,  have  been  changed  in  all  their 
parts ;  but  the  laws  which  direct  those  changes,  and  the 

153 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

rules  to  which  they  are  subject,  have  remained  invaria- 
bly the  same." 

But,  on  the  other  hand,  Hutton  and  Playfair,  and  in 
particular  Ly ell,  drew  inferences  from  this  principle 
which  the  modern  physicist  can  by  no  means  admit. 
To  them  it  implied  that  the  changes  on  the  surface  of 
the  earth  have  always  been  the  same  in  degree  as  well 
as  in  kind,  and  must  so  continue  while  present  forces 
hold  their  sway.  In  other  words,  they  thought  of  the 
world  as  a  great  perpetual-motion  machine.  But  the 
modern  physicist,  given  truer  mechanical  insight  by  the 
doctrines  of  the  conservation  and  the  dissipation  of  en- 
ergy, will  have  none  of  that.  Lord  Kelvin,  in  particular, 
has  urged  that  in  the  periods  of  our  earttrs  infancy  and 
adolescence  its  developmental  changes  must  have  been, 
like  those  of  any  other  infant  organism,  vastly  more 
rapid  and  pronounced  than  those  of  a  later  day  ;  and 
to  every  clear  thinker  this  truth  also  must  now  seem 
axiomatic. 

Whoever  thinks  of  the  earth  as  a  cooling  globe  can 
hardly  doubt  that  its  crust,  when  thinner,  may  have 
heaved  under  strain  of  the  moon's  tidal  pull — whether 
or  not  that  body  was  nearer — into  great  billows,  daily 
rising  and  falling,  like  waves  of  the  present  seas  vastly 
magnified. 

Under  stress  of  that  same  lateral  pressure  from  con- 
traction which  now  produces  the  slow  depression  of  the 
Jersey  coast,  the  slow  rise  of  Sweden,  the  occasional 
belching  of  an  insignificant  volcano,  the  jetting  of  a 
geyser,  or  the  trembling  of  an  earthquake,  once  large 
areas  were  rent  in  twain,  and  vast  floods  of  lava  flowed 
over  thousands  of  square  miles  of  the  earth's  surface 
perhaps  at  a  single  jet ;  and,  for  aught  we  know  to  the 

154 


THE  CENTURY'S  PROGRESS  IN  GEOLOGY 

contrary,  gigantic  mountains  may  have  heaped  up  their 
contorted  heads  in  cataclysms  as  spasmodic  as  even  the 
most  ardent  catastrophist  of  the  elder  day  of  geology 
could  have  imagined. 

The  atmosphere  of  that  early  day,  filled  with  vast 
volumes  of  carbon,  oxygen,  and  other  chemicals  that 
have  since  been  stored  in  beds  of  coal,  limestone,  and 


SIR   RICHARD   OWEN 


granites,  may  have  worn  down  the  rocks,  on  the  one 
hand,  and  built  up  organic  forms  on  the  other,  with  a 
rapidity  that  would  now  seem  hardly  conceivable. 
And  yet  while  all  these  anomalous  things  went  on, 

155 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

the  same  laws  held  that  now  are  operative;  and  a  true 
doctrine  of  uniforraitarianism  would  make  no  unwonted 
concession  in  conceding  them  all— though  most  of  the 
embittered  geological  controversies  of  the  middle  of  our 
century  were  due  to  the  failure  of  both  parties  to  realize 
that  simple  fact. 

And  as  of  the  past  and  present,  so  of  the  future.  The 
same  forces  will  continue  to  operate;  and  under  oper- 
ation of  these  unchanging  forces  each  day  will  differ 
from  every  one  that  has  preceded  it.  If  it  be  true,  as 
every  physicist  believes,  that  the  earth  is  a  cooling 
globe,  then,  whatever  its  present  stage  of  refrigeration, 
the  time  must  come  when  its  surface  contour  will  assume 
a  rigidity  of  level  not  yet  attained.  Then,  just  as  sure- 
ly, the  slow  action  of  the  elements  will  continue  to  wear 
away  the  land  surfaces,  particle  by  particle,  and  trans- 
port them  to  the  ocean,  as  it  does  to-day,  until,  compen- 
sation no  longer  being  afforded  by  the  upheaval  of  the 
continents,  the  last  foot  of  dry  land  will  sink  for  the 
last  time  beneath  the  water,  the  last  mountain -peak 
melting  away,  and  our  globe,  lapsing  like  any  other 
organism  into  its  second  childhood,  will  be  on  the  sur- 
face— as  presumably  it  was  before  the  first  continent 
rose — one  vast  "  waste  of  waters."  As  puny  man  con- 
ceives time  and  things,  an  awful  cycle  will  have  lapsed  ; 
in  the  sweep  of  the  cosmic  life,  a  pulse-beat  will  have 
throbbed. 


CHAPTER  V 
THE  CENTURY'S  PROGRESS  IN  METEOROLOGY 


"AN  astonishing  miracle  has  just  occurred  in  our  dis- 
trict," wrote  M.  Marais,  a  worthy  if  undistinguished 
citizen  of  France,  from  his  home  at  L'Aigle,  under  date 
of  "the  13th  Floreal,  year  11"— a  date  which  outside 
of  France  would  be  interpreted  as  meaning  May  3, 
1803.  This  "  miracle  "  was  the  appearance  of  a  "  fire- 
ball" in  broad  daylight — "perhaps  it  was  wildfire," 
says  the  nai've  chronicle  --  which  "  hung  over  the 
meadow,"  being  seen  by  many  people,  and  then  ex- 
ploded with  a  loud  sound,  scattering  thousands  of 
stony  fragments  over  the  surface  of  a  territory  some 
miles  in  extent. 

Such  a  "miracle"  could  not  have  been  announced  at 
a  more  opportune  time.  For  some  years  the  scientific 
world  had  been  agog  over  the  question  whether  such  a 
form  of  lightning  as  that  reported — appearing  in  a  clear 
sky,  and  hurling  literal  thunder-bolts — had  real  existence. 
Such  cases  had  been  reported  often  enough,  it  is  true. 
The  "thunder-bolts"  themselves  were  exhibited  as  sa- 
cred relics  before  many  an  altar,  and  those  who  doubted 
their  authenticity  had  been  chided  as  having  "an  evil 
heart  of  unbelief."  But  scientific  scepticism  had  ques- 

157 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

tioned  the  evidence,  and  late  in  the  eighteenth  century 
a  consensus  of  opinion  in  the  French  Academy  had  de- 
clined to  admit  that  such  stones  had  been  "  conveyed  to 
the  earth  by  lightning,"  let  alone  any  more  miraculous 
agency. 

In  1802,  however,  Edward  Howard  had  read  a  paper 
before  the  Royal  Society  in  which,  after  reviewing  the 
evidence  recently  put  forward,  he  had  reached  the  con- 
clusion that  the  fall  of  stones  from  the  sky,  sometimes 
or  always  accompanied  by  lightning,  must  be  admitted 
as  an  actual  phenomenon,  however  inexplicable.  ,So 
now,  when  the  great  stone-fall  at  L'Aigle  was  an- 
nounced, the  French  Academy  made  haste  to  send  the 
brilliant  young  physicist  Jean  Baptiste  Biot  to  investi- 
gate it,  that  the  matter  might,  if  possible,  be  set  finally 
at  rest.  The  investigation  was  in  all  respects  successful, 
and  Blot's  report  transferred  the  stony  or  metallic  light- 
ning-bolt—the aerolite  or  meteorite— from  the  realm  of 
tradition  and  conjecture  to  that  of  accepted  science. 

But  how  explain  this  strange  phenomenon  ?  At  once- 
speculation  was  rife.  One  theory  contended  that  the 
stony  masses  had  not  actually  fallen,  but  had  been 
formed  from  the  earth  by  the  action  of  the  lightning ; 
but  this  contention  was  early  abandoned.  The  chemists 
were  disposed  to  believe  that  the  aerolites  had  been 
formed  by  the  combination  of  elements  floating  in  the 
upper  atmosphere.  Geologists,  on  the  other  hand, 
thought  them  of  terrestrial  origin,  urging  that  they 
might  have  been  thrown  up  by  volcanoes.  The  astron- 
omers', as  represented  by  Olbers  and  Laplace,  modified 
this  theory  by  suggesting  that  the  stones  might,  indeed, 
have'  been  cast  out  by  volcanoes,  but  by  volcanoes  sit- 
uated not  on  the  earth,  but  on  the  moon. 

158 


THE  CENTURY'S   PROGRESS   IN   METEOROLOGY 

And  one  speculator  of  the  time  took  a  step  even  more 
daring,  urging  that  the  aerolites  were  neither  of  telluric 
norselenic  origin,  nor  yet  children  of  the  sun,  as  the  old 


A  METEOUIC    STONE 


Greeks  had,  many  of  them,  contended,  but  that  they 
are  visitants  from  the  depths  of  cosmic  space.  This 
bold  speculator  was  the  distinguished  German  physicist 
Ernst  F.  F.  Chladni,  a  man  of  no  small  repute  in  his 
day.  As  early  as  1794  he  urged  his  cosmical  theory 
of  meteorites,  when  the  very  existence  of  meteorites 
was  denied  by  most  scientists.  And  he  did  more :  he 

159 


THE   STORY   OF  NINETEENTH-CENTURY  SCIENCE 

declared  his  belief  that  these  falling  stones  were  really 
one  in  origin  and  kind  with  those  flashing  meteors  of 
the  upper  atmosphere  which  are  familiar  everywhere  as 
"  shooting-stars." 

Each  of  these  coruscating  meteors,  he  affirmed,  must 
tell  of  the  ignition  of  a  bit  of  cosmic  matter  entering 
the  earth's  atmosphere.  Such  wandering  bits  of  mat- 
ter might  be  the  fragments  of  shattered  worlds,  or,  as 
Chladni  thought  more  probable,  merely  aggregations 
of  "world  stuff"  never  hitherto  connected  with  any 
large  planetary  mass. 

Naturally  enough,  so  unique  a  view  met  with  very 
scant  favor.  Astronomers  at  that  time  saw  little  to  jus- 
tify it;  and  the  non-scientific  world  rejected  it  with 
fervor  as  being  "  atheistic  and  heretical,"  because  its 
acceptance  would  seem  to  imply  that  the  universe  is  not 
a  perfect  mechanism. 

Some  light  was  thrown  on  the  moot  point  presently 
by  the  observations  of  Brandes  and  Benzenberg,  which 
tended  to  show  that  falling-stars  travel  at  an  actual 
speed  of  from  fifteen  to  ninety  miles  a  second.  This 
observation  tended  to  discredit  the  selenic  theory,  since 
an  object,  in  order  to  acquire  such  speed  in  falling  mere- 
ly from  the  moon,  must  have  been  projected  with  an  in- 
itial velocity  not  conceivably  to  be  given  by  any  lunar 
volcanic  impulse.  Moreover,  there  was  a  growing  con- 
viction that  there  are  no  active  volcanoes  on  the  moon, 
and  other  considerations  of  the  same  tenor  led  to  the 
complete  abandonment  of  the  selenic  theory. 

But  the  theory  of  telluric  origin  of  aerolites  was  by 
no  means  so  easily  disposed  of.  This  was  an  epoch 
when  electrical  phenomena  were  exciting  unbounded 
and  universal  interest,  and  there  was  a  not  unnatural 

160 


THE  CENTURY'S   PROGRESS   IN   METEOROLOGY 

tendency  to  appeal  to  electricity  in  explanation  of  every 
obscure  phenomenon ;  and  in  this  case  the  seeming  sim- 
ilarity between  a  lightning-flash  and  the  flash  of  an 
aerolite  lent  color  to  the  explanation.  So  we  find 
Thomas  Forster,  a  meteorologist  of  repute,  still  adher- 
ing to  the  atmospheric  theory  of  formation  of  aerolites 
in  his  book  published  in  1823  ;  and,  indeed,  the  prevail- 
ing opinion  of  the  time  seemed  divided  between  various 
telluric  theories,  to  the  neglect  of  any  cosmical  theory 
whatever. 

But  in  1833  occurred  a  phenomenon  which  set  the 
matter  finally  at  rest.  A  great  meteoric  shower  oc- 
curred in  November  of  that  year,  and  in  observing  it 
Professor  Denison  Olmsted,  of  Yale,  noted  that  all  the 
stars  of  the  shower  appeared  to  come  from  a  single 
centre  or  vanishing-point  in  the  heavens,  and  that 
this  centre  shifted  its  position  with  the  stars,  and  hence 
was  not  telluric.  The  full  significance  of  this  obser- 
vation was  at  once  recognized  by  astronomers  ;  it  de- 
monstrated beyond  all  cavil  the  cosmical  origin  of  the 
shooting-stars.  Some  conservative  meteorologists  kept 
up  the  argument  for  the  telluric  origin  for  some  decades 
to  come  as  a  matter  of  course — such  a  band  trails  alwa}7s 
in  the  rear  of  progress.  But  even  these  doubters  were 
silenced  when  the  great  shower  of  shooting-stars  ap- 
peared again  in  1866,  as  predicted  by  Olbers  and  New- 
ton, radiating  from  the  same  point  of  the  heavens  as 
before. 

Since  then  the  spectroscope  has  added  its  confirmatory 
evidence  as  to  the  identity  of  meteorite  and  shooting- 
star,  and,  moreover,  has  linked  these  atmospheric  meteors 
with  such  distant  cosmic  residents  as  comets  and  nebulae. 
Thus  it  appears  that  Chladni's  daring  hypothesis  of  1794 
L  161 


T1IE  STORY   OF   NINETEENTH-CENTURY  SCIENCE 

has  been  more' than  verified,  and  that  the  fragments  of 
matter  dissociated  from  planetary  connection— which  he 
postulated  and  was  declared  atheistic  for  postulating — 
have  been  shown  to  be  billions  of  times  more  numerous 
than  any  larger  cosmic  bodies  of  which  we  have  cog- 
nizance— so  widely  does  the  existing  universe  differ  from 
man's  preconceived  notions  as  to  what  it  should  be. 

Thus  also  the  "  miracle  "  of  the  falling  stone,  against 
which  the  scientific  scepticism  of  yesterday  presented 
"  an  evil  heart  of  unbelief,"  turns  out  to  be  the  most 
natural  of  phenomena,  inasmuch  as  it  is  repeated  in  our 
atmosphere  some  millions  of  times  each  day. 


IT 

* 

If  fire-balls  were  thought  miraculous  and  portentous 
in  daj^s  of  yore,  what  interpretation  must  needs  have 
been  put  upon  that  vastly  more  picturesque  phenom- 
enon, the  aurora?  "Through  all  the  city,"  says  the 
Book  of  Maccabees,  "  for  the  space  of  almost  forty  days, 
there  were  seen  horsemen  running  in  the  air,  in  cloth 
of  gold,  armed  with  lances,  like  a  band  of  soldiers :  and 
troops  of  horsemen  in  array  encountering  and  running 
one  against  another,  with  shaking  of  shields  and  multi- 
tude of  pikes,  and  drawing  of  swords,  and  casting  of 
darts,  and  glittering  of  golden  ornaments  and  harness." 
Dire  omens  these ;  and  hardly  less  ominous  the  aurora 
seemed  to  all  succeeding  generations  that  observed  it 
down  till  well  into  the  eighteenth  century— as  witness 
the  popular  excitement  in  England  in  1716  over  the 
brilliant  aurora  of  that  year,  which  became  famous 
through  Halley's  description. 

But  after  1752,  when  Franklin  dethroned  the  light- 

162 


THE  CENTURY'S   PROGRESS   IN   METEOROLOGY 

ning,  all  spectacular  meteors  came  to  be  regarded  as 
natural  phenomena,  the  aurora  among  the  rest.  Frank- 
lin explained  the  aurora — which  was  seen  commonly 
enough  in  the  eighteenth  century,  though  only  recorded 


CIRRUS  CLOUDS 

once  in  the  seventeenth — as  due  to  the  accumulation  of 
electricity  on  the  surface  of  polar  snows,  and  its  dis- 
charge to  the  equator  through  the  upper  atmosphere. 
Erasmus  Darwin  suggested  that  the  luminosity  might  be 
due  to  the  ignition  of  hydrogen,  which  was  supposed  by 
many  philosophers  to  form  the  upper  atmosphere.  Dai- 
ton,  who  first  measured  the  height  of  the  aurora,  esti- 
mating it  at  about  one  hundred  miles,  thought  the  phe- 
nomenon due  to  magnetism  acting  on  ferruginous 
particles  in  the  air,  and  his  explanation  was  perhaps 
the  most  popular  one  at  the  beginning  of  the  century. 

163 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

Since  then  a  multitude  of  observers  have  studied  the 
aurora,  but  the  scientific  grasp  has  found  it  as  elusive  in 
fact  as  it  seems  to  casual  observation,  and  its  exact  nat- 
ure is  as  undetermined  to-day  as  it  was  a  hundred  years 
ago.  There  has  been  no  dearth  of  theories  concerning 
it,  however.  Biot,  who  studied  it  in  the  Shetland  Isl- 
ands in  1817,  thought  it  due  to  electrified  ferruginous 
dust,  the  origin  of  which  he  ascribed  to  Icelandic  vol- 
canoes. Much  more  recently  the  idea  of  ferruginous 
particles  has  been  revived,  their  presence  being  ascribed 
not  to  volcanoes,  but  to  the  meteorites  constantly  being 
dissipated  in  the  upper  atmosphere.  Ferruginous  dust, 
presumably  of  such  origin,  has  been  found  on  the  polar 
snows,  as  well  as  on  the  snows  of  mountain-tops,  but 
whether  it  could  produce  the  phenomena  of  auroras  is 
at  least  an  open  question. 

Other  theorists  have  explained  the  aurora  as  due  to 
the  accumulation  of  electricity  on  clouds  or  on  spicules 
of  ice  in  the  upper  air.  Yet  others  think  it  due  merely 
to  the  passage  of  electricity  through  rarefied  air  itself. 
Humboldt  considered  the  matter  settled  in  yet  another 
way  when  Faraday  showed,  in  1831,  that  magnetism 
may  produce  luminous  effects.  But  perhaps  the  pre- 
vailing theory  of  to-day  assumes  that  the  aurora  is  due 
to  a  current  of  electricity  generated  at  the  equator,  and 
passing  through  upper  regions  of  space,  to  enter  the 
earth  at  the  magnetic  poles — simply  reversing  the  course 
which  Franklin  assumed. 

The  similarity  of  the  auroral  light  to  that  generated 
in  a  vacuum  bulb  by  the  passage  of  electricity  lends 
support  to  the  long-standing  supposition  that  the  aurora 
is  of  electrical  origin,  but  the  subject  still  awaits  com- 
plete elucidation.  For  once  even  that  mystery-solver 

164 


TilE  CENTURY'S   PROGRESS   IN   METEOROLOGY 

the  spectroscope  has  been  baffled,  for  the  line  it  sifts 
from  the  aurora  is  not  matched  by  that  of  any  recog- 
nized substance.  A  like  line  is  found  in  the  zodiacal 
light,  it  is  true,  but  this  is  of  little  aid,  for  the  zodiacal 
light,  though  thought  by  some  astronomers  to  be  due  to 
meteor  swarms  about  the  sun,  is  held  to  be,  on  the 
whole,  as  mysterious  as  the  aurora  itself. 

Whatever  the  exact  nature  of  the  aurora,  it  has  long 
been  known  to  be  intimately  associated  with  the  phe- 
nomena of  terrestrial  magnetism.  Whenever  a  brilliant 


CUMULUS  CLOUDS 


aurora  is  visible,  the  world  is  sure  to  be  visited  with 
what  Humboldt  called  a  magnetic  storm — a  "  storm  " 
which  manifests  itself  to  human  senses  in  no  way  what- 
soever except  by  deflecting  the  magnetic  needle  and 

165 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

conjuring  with  the  electric  wire.  Such  magnetic  storms 
are  curiously  associated  also  with  spots  on  the  sun — just 
how  no  one  has  explained,  though  the  fact  itself  is  un- 
questioned. Sun-spots,  too,  seem  directly  linked  with 
auroras,  each  of  these  phenomena  passing  through  peri- 
ods of  greatest  and  least  frequency  in  corresponding 
cycles  of  about  eleven  years'  duration. 

It  was  suspected  a  full  century  ago  by  Herschel  that 
the  variations  in  the  number  of  sun-spots  had  a  direct 
effect  upon  terrestrial  weather,  and  he  attempted  to 
demonstrate  it  by  using  the  price  of  wheat  as  a  criterion 
of  climatic  conditions,  meantime  making  careful  observa- 
tion of  the  sun-spots.  Nothing  very  definite  came  of  his 
efforts  in  this  direction,  the  subject  being  far  too  complex 
to  be  determined  without  long  periods  of  observation. 
Latterly,  however,  meteorologists,  particularly  in  the 
tropics,  are  disposed  to  think  they  find  evidence  of  some 
such  connection  between  sun-spots  and  the  weather  as 
Herschel  suspected.  Indeed,  Mr.  Meld  rum  declares  that 
there  is  a  positive  coincidence  between  periods  of  numer- 
ous sun-spots  and  seasons  of  excessive  rain  in  India. 

That  some  such  connection  does  exist  seems  intrinsi- 
cally probable.  But  the  modern  msteorologist,  learning 
wisdom  of  the  past,  is  extremely  cautious  about  ascribing 
casual  effects  to  astronomical  phenomena.  He  finds  it 
hard  to  forget  that  until  recently  all  manner  of  climatic 
conditions  were  associated  with  phases  of  the  moon ; 
that  not  so  very  long  ago  showers  of  falling-stars  were 
considered  u prognostic "  of  certain  kinds  of  weather; 
and  that  the  "equinoctial  storm"  had  been  accepted  as 
a  verity  by  every  one,  until  the  unfeeling  hand  of  statis- 
tics banished  it  from  the  earth. 

Yet,  on  the  other  hand,  it  is  easily  within  the  possi- 

166 


THE   CENTURY'S   PROGRESS   IN  METEOROLOGY 

bilities  that  the  science  of  the  future  may  reveal  associa- 
tions between  the  weather  and  sun-spots,  auroras,  and 
terrestrial  magnetism  that  as  yet  are  hardly  dreamed  of. 
Until  such  time,  however,  these  phenomena  must  feel 
themselves  very  grudgingly  admitted  to  the  inner  circle 
of  meteorology.  More  and  more  this  science  concerns 
itself,  in  our  age  of  concentration  and  specialization, 
with  weather  and  climate.  Its  votaries  no  longer  con- 
cern themselves  with  stars  or  planets  or  comets  or  shoot- 
ing-stars— once  thought  the  very  essence  of  guides  to 
weather  wisdom ;  and  they  are  even  looking  askance  at 
the  moon,  and  asking  her  to  show  cause  why  she  also 
should  not  be  excluded  from  their  domain.  Equally 
little  do  they  care  for  the  interior  of  the  earth,  since 
they  have  learned  that  the  central  emanations  of  heat 
which  Mairan  imagined  as  a  main  source  of  aerial 
warmth  can  claim  no  such  distinction.  Even  such  prob- 
lems as  why  the  magnetic  pole  does  not  coincide  with 
the  geographical,  and  why  the  force  of  terrestrial  mag- 
netism decreases  from  the  magnetic  poles  to  the  mag- 
netic equator,  as  Humboldt  first  discovered  that  it  does, 
excite  them  only  to  lukewarm  interest;  for  magnetism, 
they  say,  is  not  known  to  have  any  connection  whatever 
with  climate  or  weather. 

in 

There  is  at  least  one  form  of  meteor,  however,  of  those 
that  interested  our  forebears,  whose  meteorological  im- 
portance they  did  not  overestimate.  This  is  the  vapor 
of  water.  How  great  was  the  interest  in  this  familiar 
meteor  at  the  beginning  of  the  century  is  attested  by  the 
number  of  theories  then  extant  regarding  it;  and  these 
conflicting  theories  bear  witness  also  to  the  difficulty 

167 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

with  which  the  familiar  phenomenon  of  the  evaporation 
of  water  was  explained. 

Franklin  had  suggested  that  air  dissolves  water  much 
as  water  dissolves  salt,  and  this  theory  was  still  popular, 


STRATUS  CLOUDS 


though  Deluc  had  disproved  it  by  showing  that  water 
evaporates  even  more  rapidly  in  a  vacuum  than  in  air. 
Deluc's  own  theory,  borrowed  from  earlier  chemists, 
was  that  evaporation  is  the  chemical  union  of  particles 
of  water  with  particles  of  the  supposititious  element  heat. 
Erasmus  Darwin  combined  the  two  theories,  suggesting 
that  the  air  might  hold  a  variable  quantity  of  vapor  in 
mere  solution,  and  in  addition  a  permanent  moiety  in 
chemical  combination  with  caloric. 

Undisturbed  by  these  conflicting  views,  that  strangely 
original  genius,  John  Dalton,  afterwards  to  be  known  as 

168 


THE  CENTURY'S    PROGRESS   IN   METEOROLOGY 

perhaps  the  greatest  of  theoretical  chemists,  took  the 
question  in  hand,  and  solved  it  by  showing  that  water 
exists  in  the  air  as  an  utterly  independent  gas.  He 
reached  a  partial  insight  into  the  matter  in  1793,  when 
his  first  volume  of  meteorological  essays  was  published; 
but  the  full  elucidation  of  the  problem  came  to  him  in 
1801.  The  merit  of  his  studies  was  at  once  recognized, 
but  the  tenability  of  his  hypothesis  was  long  and  ardently 
disputed. 

While  the  nature  of  evaporation  was  in  dispute,  as  a 
matter  of  course  the  question  of  precipitation  must  be 
equally  undetermined.  The  most  famous  theory  of  the 
period  was  that  formulated  by  Dr.  Hutton  in  a  paper 
read  before  the  Royal  Society  of  Edinburgh,  and  pub- 
lished in  the  volume  of  transactions  which  contained 
also  the  same  author's  epoch-making  paper  on  geology. 
This  "theory  of  rain"  explained  piecipitation  as  due  to 
the  cooling  of  a  current  of  saturated  air  by  contact  with 
a  colder  current,  the  assumption  being  that  the  surplus- 
age of  moisture  was  precipitated  in  a  chemical  sense, 
just  as  the  excess  of  salt  dissolved  in  hot  water  is  pre- 
cipitated when  the  water  cools.  The  idea  that  the  cool- 
ing of  the  saturated  air  causes  the  precipitation  of  its 
moisture  is  the  germ  of  truth  that  renders  this  paper  of 
Hutton's  important.  All  correct  later  theories  build  on 
this  foundation. 

The  next  ambitious  attempt  to  explain  the  phenomena 
of  aqueous  meteors  was  made  by  Luke  Howard,  in  his 
remarkable  paper  on  clouds,  published  in  the  Philosoph- 
ical Magazine  in  1803 — the  paper  in  which  the  names 
cirrus,  cumulus,  stratus,  etc.,  afterwards  so  universally 
adopted,  were  first  proposed.  In  this  paper  Howard^ 
acknowledges  his  indebtedness  to  Dalton  for  the  theory 

169 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

of  evaporation,  yet  he  still  clings  to  the  idea  that  the 
vapor,  though  independent  of  the  air,  is  combined  with 
particles  of  caloric.  He  holds  that  clouds  are  composed 
of  vapor  that  has  previously  risen  from  the  earth,  com- 
bating the  opinions  of  those  who  believe  that  they  are 
formed  by  the  union  of  hydrogen  and  oxygen  existing 
independently  in  the  air;  though  he  agrees  with  these 
theorists  that  electricity  has  entered  largely  into  the 
modus  operandi  of  cloud  formation.  He  opposes  the 
opinion  of  Deluc  and  de  Saussure  that  clouds  are  com- 
posed of  particles  of  water  in  the  form  of  hollow  vesicles 
(miniature  balloons,  in  short,  perhaps  filled  with  hydro- 
gen), which  untenable  opinion  was  a  revival  of  the  theory 
as  to  the  formation  of  all  vapor  which  Dr.  Halley  had 
advocated  early  in  the  eighteenth  century. 

Of  particular  interest  are  Howard's  views  as  to  the 
formation  of  dew,  which  he  explains  as  caused  by  the 
particles  of  caloric  forsaking  the  vapor  to  enter  the  cool 
body,  leaving  the  water  on  the  surface.  This  comes  as 
near  the  truth  perhaps  as  could  be  expected  while  the 
old  idea  as  to  the  materiality  of  heat  held  sway.  How- 
ard believed,  however,  that  dew  is  usually  formed  in 
the  air  at  some  height,  and  that  it  settles  to  the  surface, 
opposing  the  opinion,  which  had  gained  vogue  in  France 
and  in  America  (where  Noah  Webster  prominently  ad- 
vocated it),  that  dew  ascends  from  the  earth. 

The  complete  solution  of  the  problem  of  dew  forma- 
tion— which  really  involved  also  the  entire  question  of 
precipitation  of  watery  vapor  in  any  form — was  made 
by  Dr.  C.  W.  Wells,  a  man  of  American  birth,  whose  life, 
however,  after  boyhood,  was  spent  in  Scotland  (where 
as  a  young  man  he  enjoyed  the  friendship  of  David 
Hume)  and  in  London.  Inspired  no  doubt  by  the  re- 

170 


THE   CEXTURY'S   PROGRESS   IN  METEOROLOGY 

searches  of  Black,  Hutton,  and  their  confreres  of  that 
Edinburgh  school,  Wells  made  observations  on  evapora- 
tion and  precipitation  as  early  as  1784,  but  other  things 
claimed  his  attention ;  and  though  he  asserts  that  the 
subject  was  often  in  his  mind,  he  did  not  take  it  up 
again  in  earnest  until  about  1812. 

Meantime  the  observations  on  heat  of  Rumford  and 
Davy  and  Leslie  had  cleared  the  way  for  a  proper  in- 
terpretation of  the  facts — about  the  facts  themselves 
there  had  long  been  practical  unanimity  of  opinion.  Dr. 
Black,  with  his  latent-heat  observations,  had  really  given 
the  clew  to  all  subsequent  discussions  of  the  subject  of 
precipitation  of  vapor;  and  from  his  time  on  it  had  been 
known  that  heat  is  taken  up  when  water  evaporates, 
and  given  out  again  when  it  condenses.  Dr.  Darwin 
had  shown  in  1788,  in  a  paper  before  the  Royal  Society, 
that  air  gives  off  heat  on  contracting,  and  takes  it  up  on 
expanding;  and  Dalton  in  his  essay  of  1793  had  ex- 
plained this  phenomenon  as  due  to  the  condensation  and 
vaporization  of  the  water  contained  in  the  air. 

But  some  curious  and  puzzling  observations  which 
Professor  Patrick  Wilson,  Professor  of  Astronomy  in 
the  Universit}7  of  Glasgow,  had  communicated  to  the 
Royal  Society  of  Edinburgh  in  1784,  and  some  similar 
ones  made  by  Mr.  Six  of  Canterbury  a  few  years  later, 
had  remained  unexplained.  Both  these  gentlemen  ob- 
served that  the  air  is  cooler  where  dew  is  forming  than 
the  air  a  few  feet  higher,  and  they  inferred  that  the  dew 
in  forming  had  taken  up  heat,  in  apparent  violation  of 
established  physical  principles. 

It  remained  foV  Wells,  in  his  memorable  paper  of 
1816,  to  show  that  these  observers  had  simply  gotten 
the  cart  before  the  horse.  He  made  it  clear  that  the 

171 


THE   STOliY  OF  NINETEENTH-CENTURY   SCIENCE 

air  is  not  cooler  because  the  dew  is  formed,  but  that  the 
dew  is  formed  because  the  air  is  cooler — having  become 
so  through  radiation  of  heat  from  the  solids  on  which 
the  dew  forms.  The  dew  itself,  in  forming,  gives  out 
its  latent  heat,  and  so  tends  to  equalize  the  temperature. 
This  explanation  made  it  plain  why  dew  forms  on  a 
clear  night,  when  there  are  no  clouds  to  reflect  the  radi- 
ant heat.  Combined  with  Dalton's  theory  that  vapor 
is  an  independent  gas,  limited  in  quantity  in  any  given 
space  by  the  temperature  of  that  space,  it  solved  the 
problem  of  the  formation  of  clouds,  rain,  snow,  and 
hoar-frost.  Thus  this  paper  of  Weils's  closed  the  epoch 
of  speculation  regarding  this  field  of  meteorology,  as 
Hutton's  paper  of  1784  had  opened  it.  The  fact  that 
the  volume  containing  Hutton's  paper  contained  also 
his  epoch-making  paper  on  Geology,  finds  curiously  a 
duplication  in  the  fact  that  Weils's  volume  contained 
also  his  essay  on  Albinism,  in  which  the  doctrine  of 
natural  selection  was  for  the  first  time  formulated,  as 
Charles  Darwin  freely  admitted  after  his  own  efforts 
had  made  the  doctrine  famous. 


IV 

The  very  next  year  after  Dr.  Weils's  paper  was  pub- 
lished, there  appeared  in  France  the  third  volume  of  the 
Memoires  de  Physique  et  de  C/iimie  de  la  Societe  d'Ar- 
cueil,  and  a  new  epoch  in  meteorology  was  inaugurated. 
The  society  in  question  was  numerically  an  inconse- 
quential band,  listing  only  a  dozen  members.  But  every 
name  was  a  famous  one :  Arago,  Berard,  Berthollet, 
Biot,  Chaptal,  de  Candolle,  Dulong,  Gay-Lussac,  Hum- 
boldt,  Laplace,  Poisson,  and  Thenard — rare  spirits  every 

173 


JEAN  BAPTISTE  BIOT 


THE  CENTURY'S  PROGRESS   IN  METEOROLOGY 

one.  Little  danger  that  the  memoirs  of  such  a  band 
would  be  relegated  to  the  dusty  shelves  where  most 
proceedings  of  societies  belong — no  milk-for-ba^es  fare 
would  be  served  to  such  a  company. 

The  particular  paper  which  here  interests  us  closes 
this  third  and  last  volume  of  memoirs.  It  is  entitled  Des 
lignes  isothermes  et  de  la  distribution  de  la  chaleur  sur  le 
globe.  The  author  is  Alexander  Plumboldt.  Needless 
to  say,  the  topic  is  handled  in  a  masterly  manner.  The 
distribution  of  heat  on  the  surface  of  the  globe,  on  the 
mountain-sides,  in  the  interior  of  the  earth  ;  the  causes 
that  regulate  such  distribution;  the  climatic  results — 
these  are  the  topics  discussed.  But  what  gives  epochal 
character  to  the  paper  is  the  introduction  of  those  iso- 
thermal lines,  circling  the  earth  in  irregular  course,  join- 
ing together  places  having  the  same  mean  annual  tem- 
perature, and  thus  laying  the  foundation  for  a  science  of 
comparative  climatology. 

It  is  true  the  attempt  to  study  climates  comparatively 
was  not  new.  Mairan  had  attempted  it  in  those  papers 
in  which  he  developed  his  bizarre  ideas  as  to  central 
emanations  of  heat.  Euler  had  brought  his  profound 
mathematical  genius  to  bear  on  the  topic,  evolving  the 
"  extraordinary  conclusion  that  under  the  equator  at 
midnight  the  cold  ought  to  be  more  rigorous  than  at 
the  poles  in  winter."  And  in  particular  Richard  Kir- 
wan,  the  English  chemist,  had  combined  the  mathemat- 
ical and  the  empirical  methods,  and  calculated  temper- 
atures for  all  latitudes.  But  Humboldt  differs  from  all 
these  predecessors  in  that  he  grasps  the  idea  that  the 
basis  of  all  such  computations  should  be  not  theory,  but 
fact.  He  drew  his  isothermal  lines  not  where  some  oc- 
cult, calculation  would  locate  them  on  an  ideal  globe, 

175 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

but  where  practical  tests  with  the  thermometer  locate 
them  on  our  globe  as  it  is.  London,  for  example,  lies  in 
the  same  latitude  as  the  southern  extremity  of  Hudson 
Bay  ;  but  the  isotherm  of  Loadon,  as  Humboldt  outlines 
it,  passes  through  Cincinnati. 

Of  course  such  deviations  of  climatic  conditions  be- 
tween places  in  the  same  latitude  had  long  been  known. 
As  Humboldt  himself  observes,  the  earliest  settlers  of 
America  were  astonished  to  find  themselves  subjected 
to  rigors  of  climate  for  which  their  European  experience 
had  not  at  all  prepared  therm  Moreover,  sagacious 
travellers,  in  particular  Cook's  companion  on  his  second 
voyage,  young  George  Forster,  had  noted  as  a  general 
principle  that  the  western  borders  of  continents  in  tem- 
perate regions  are  always  warmer  than  corresponding 
latitudes  of  their  eastern  borders;  and  of  course  the 
general  truth  of  temperatures  being  milder  in  the  vicin- 
ity of  the  sea  than  in  the  interior  of  continents  had  long 
been  familiar.  But  Humboldt's  isothermal  lines  for  the 
first  time  gave  tangibility  to  these  ideas,  and  made  prac- 
ticable a  truly  scientific  study  of  comparative  climatol- 
ogy- 

In  studying  these  lines,  particularly  as  elaborated  by 
further  observations,  it  became  clear  that  they  are  by 
no  means  haphazard  in  arrangement,  but  are  dependent 
upon  geographical  conditions  which  in  most  cases  are  not 
difficult  to  determine.  Humboldt  himself  pointed  out 
very  clearly  the  main  causes  that  tend  to  produce  de- 
viations from  the  average — or,  as  Dove  later  on  called 
it,  the  normal — temperature  of  any  given  latitude.  For 
example,  the  mean  annual  temperature  of  a  region  (re- 
ferring mainly  to  the  northern  hemisphere)  is  raised  by 
the  proximity  of  a  western  coast ;  by  a  divided  config- 

176 


THE   CENTURY'S   PROGRESS   IN  METEOROLOGY 

urationof  the  continent  into  peninsulas  ;  by  the  existence 
of  open  seas  to  the  north  or  of  radiating  continental 
surfaces  to  the  south ;  by  mountain  ranges  to  shield 
from  cold  winds ;  by  the  infrequency  of  swamps  to  be- 
come congealed  ;  by  the  absence  of  woods  in  a  dry, 
sandy  soil ;  and  by  the  serenity  of  sky  in  the  summer 
months,  and  the  vicinity  of  an  ocean  current  bringing 
water  which  is  of  a  higher  temperature  than  that  of  the 
surrounding  sea. 

Conditions  opposite  to  these  tend,  of  course,  corre- 
spondingly to  lower  the  temperature.  In  a  word,  Hum- 
boldt  says  the  climatic  distribution  of  heat  depends  on 
the  relative  distribution  of  land  and  sea,  and  on  the 
"  hypsometrical  configuration  of  the  continents  "  ;  and 
he  urges  that  "  great  meteorological  phenomena  cannot 
be  comprehended  when  considered  independently  of 
geognostic  relations  " — a  truth  which,  like  most  other 
general  principles,  seems  simple  enough  once  it  is 
pointed  out. 

With  that  broad  sweep  of  imagination  which  charac- 
terized him,  Hum  bold  t  speaks  of  the  atmosphere  as  the 
"aerial  ocean,  in  the  lower  strata  and  on  the  shoals  of 
which  we  live,"  and  he  studies  the  atmospheric  phe- 
nomena always  in  relation  to  those  of  that  other  ocean 
of  water.  In  each  of  these  oceans  there  are  vast  per- 
manent currents,  flowing  always  in  determinate  direc- 
tions, which  enormously  modify  the  climatic  conditions 
of  every  zone.  The  ocean  of  air  is  a  vast  maelstrom, 
boiling  up  always  under  the  influence  of  the  sun's  heat 
at  the  equator,  and  flowing  as  an  upper  current  towards 
either  pole,  while  an  under  current  from  the  poles,  which 
becomes  the  trade- winds,  flows  towards  the  equator  to 

supply  its  place. 

M  177 


THE   STORY  OF   NINETEENTH-CENTURY   SCIENCE 

But  the  superheated  equatorial  air,  becoming  chilled, 
descends  to  the  surface  in  temperate  latitudes,  and  con- 
tinues its  poleward  journey  as  the,  anti-trade-winds. 
The  trade- winds  are  deflected  towards  the  west,  because 
in  approaching  the  equator  they  constantly  pass  over 
surfaces  of  the  earth  having  a  greater  and  greater  veloc- 
ity of  rotation,  and  so,  as  it  were,  tend  to  lag  behind— 
an  explanation  which  Hadley  pointed  out  in  1735,  but 
which  was  not  accepted  until  Dal  ton  independently 
worked  it  out  and  promulgated  it  in  1793.  For  the 
opposite  reason,  the  anti-trades  are  deflected  towards 
the  east ;  hence  it  is  that  the  western  borders  of  con- 
tinents in  temperate  zones  are  bathed  in  moist  sea- 
breezes,  while  their  eastern  borders  lack  this  cold-dis- 
pelling influence.. 

In  the  ocean  of  water  the  main  currents  run  as  more 
sharply  circumscribed  streams — veritable  rivers  in  the  sea. 
Of  these  the  best  known  and  most  sharply  circumscribed 
is  the  familiar  Gulf  Stream,  which  has  its  origin  in  an 
equatorial  current,  impelled  westward  by  trade-winds, 
which  is  deflected  northward  in  the  main  at  Cape  St. 
Roque,  entering  the  Caribbean  Sea  and  Gulf  of  Mexico, 
to  emerge  finally  through  the  Strait  of  Flor-ida,  and 
journey  off  across  the  Atlantic  to  warm  the  shores  of 
Europe. 

Such,  at  least,  is  the  Gulf  Stream  as  Humboldt  under- 
stood it.  Since  his  time,  however,  ocean  currents  in 
general,  and  this  one  in  particular,  have  been  the  subject 
of  no  end  of  controversy,  it  being  hotly  disputed  whether 
either  causes  or  effects  of  the  Gulf  Stream  are  just  what 
Humboldt,  in  common  with  others  of  his  time,  con- 
ceived them  to  be.  About  the  middle  of  the  century, 
Lieutenant  M.  F.  Maury,  the  distinguished  American 

178 


THE   CENTURY'S   PROGRESS   IN   METEOROLOGY 

h}7drographer  and  meteorologist,  advocated  a  theory  of 
gravitation  as  the  chief  cause  of  the  currents,  claiming 
that  difference  in  density,  due  to  difference  in  temper- 
ature and  saltness,  would  sufficiently  account  for  the 


LIEUTENANT  MATTHEW   FONTAINE   MAURY 

oceanic  circulation.  This  theory  gained  great  popularity 
through  the  wide  circulation  of  Maury's  Physical  Geog- 
raphy of  the  Sea,  which  is  said  to  have  passed  through 
more  editions  than  an  other  scientific  book  of  the 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

period  ;  but  it  was  ably  and  vigorously  combated  by  Dr. 
James  Croll,  the  Scottish  geologist,  in  his  Climate  and 
Time,  and  latterly  the  old  theory  that  ocean  currents 
are  due  to  the  trade- winds  has  again  come  into  favor. 
Indeed,  very  recently  a  model  has  been  constructed,  with 
the  aid  of  which  it  is  said  to  have  been  demonstrated 
that  prevailing  winds  in  the  direction  of  the  actual  trade- 
winds  would  produce  such  a  current  as  the  Gulf  Stream. 

Meantime,  however,  it  is  by  no  means  sure  that  gravi- 
tation does  not  enter  into  the  case  to  the  extent  of  pro- 
ducing an  insensible  general  oceanic  circulation,  inde- 
pendent of  the  Gulf  Stream  and  similar  marked  currents, 
and  similar  in  its  larger  outlines  to  the  polar-equatorial 
circulation  of  the  air.  The  idea  of  such  oceanic  circula- 
tion was  first  suggested  in  detail  by  Professor  Lenz  of 
St.  Petersburg,  in  1845,  but  it  was  not  generally  recog- 
nized until  Dr.  Carpenter  independently  hit  upon  the 
idea  more  than  twenty  years  later.  The  plausibility  of 
the  conception  is  obvious ;  yet  the  alleged  fact  of  such 
circulation  has  been  hotly  disputed,  and  the  question  is 
still  siib  judice. 

But  whether  or  not  such  general  circulation  of  ocean 
water  takes  place,  it  is  beyond  dispute  that  the  recog- 
nized currents  carry  an  enormous  quantity  of  heat  from 
the  tropics  towards  the  poles.  Dr.  Croll,  who  has  per- 
haps given  more  attention  to  the  physics  of  the  subject 
than  almost  any  other  person,  computes  that  the  Gulf 
Stream  conveys  to  the  North  Atlantic  one-fourth  as 
much  heat  as  that  body  receives  directly  from  the  sun, 
and  he  argues  that  'were  it  not  for  the  transportation  of 
heat  by  this  and  similar  Pacific  currents,  only  a  narrow 
tropical  region  of  the  globe  would  be  warm  enough  for 
habitation  by  the  existing  faunas.  Dr.  Croll  argues  that 

180 


THE   CENTURY'S   PROGRESS   IN   METEOROLOGY 

a  slight  change  in  the  relative  values  of  northern  and 
southern  trade-winds  (such  as  he  believes  has  taken 
place  at  various  periods  in  the  past)  would  suffice  to  so 
alter  the  equatorial  current  which  now  feeds  the  Gfilf 
Stream  that  its  main  bulk  would  be  deflected  southward 
instead  of  northward,  by  the  angle  of  Cape  St.  Roque. 
Thus  the  Gulf  Stream  would  be  nipped  in  the  bud,  and, 
according  to  Dr.  Croll's  estimates,  the  results  would  be 
disastrous  for  the  northern  hemisphere.  The  anti-trades, 
which  now  are  warmed  by  the  Gulf  Stream,  would  then 
blow  as  cold  winds  across  the  shores  of  western^  Europe, 
and  in  all  probability  a  glacial  epoch  would  supervene 
throughout  the  northern  hemisphere. 

The  same  consequences,  so  far  as  Europe  is  con- 
cerned at  least,  would  apparently  ensue  were  the  Isth- 
mus of  Panama  to  settle  into  the  sea,  allowing  the  Ca- 
ribbean current  to  pass  into  the  Pacific.  But  the  geol- 
ogist tells  us  that  this  isthmus  rose  at  a  comparatively 
recent  geological  period,  though  it  is  hinted  that  there 
had  been  some  time  previously  a  temporary  land  con- 
nection between  the  two  continents.  Are  we  to  infer, 
then,  that  the  two  Americas  in  their  unions  and  dis- 
unions have  juggled  with  the  climate  of  "the  other  hem- 
isphere ?  Apparently  so,  if  the  estimates  made  of  the 
influence  of  the  Gulf  Stream  be  tenable.  It  is  a  far  cry 
from  Panama  to  Russia.  Yet  it  seems  within  the  possi- 
bilities that  the  meteorologist  may  learn  from  the  geolo- 
gist of  Central  America  something  that  will  enable  him 
to  explain  to  the  paleontologist  of  Europe  how  it 
chanced  that  at  one  time  the  mammoth  and  rhinoceros 
roamed  across  northern  Siberia,  while  at  another  time 
the  reindeer  and  musk-ox  browsed  along  the  shores  of 
the  Mediterranean. 

181 


THE   STORY  OF  NINETEENTH-CENT UKY  SCIENCE 

Possibilities,  I  said,  not  probabilities.  Yet  even  the 
faint  glimmer  of  so  alluring  a  possibility  brings  home  to 
one  with  vividness  the  truth  of  Humboldt's  perspicuous 
observation  that  meteorology  can  be  properly  compre- 
hended only  when  studied  in  connection  with  the  com- 
panion sciences.  There  are  no  isolated  phenomena  in 
nature. 


Yet,  after  all,  it  is  not  to  be  denied  that  the  chief 
concern  of  the  meteorologist  must  be  with  that  other 
medium,  the  "  ocean  of  air,  on  the  shoals  of  which  we 
live."  For  whatever  may  be  accomplished  by  water 
currents  in  the  way  of  conveying  heat,  it  is  the  wind 
currents  that  effect  the  final  distribution  of  that  heat. 
As  Dr.  Croll  has  urged,  the  waters  of  the  Gulf  Stream 
do  not  warm  the  shores  of  Europe  by  direct  contact, 
but  by  warming  the  anti-trade-winds,  which  subsequent- 
ly blow  across  the  continent.  And  everywhere  the 
heat  accumulated  by  water  becomes  effectual  in  modi- 
fying climate,  not  so  much  by  direct  radiation  as  by  dif- 
fusion through  the  medium  of  the  air. 

This  very  obvious  importance  of  aerial  currents  led 
to  their  practical  study  long  before  meteorology  had 
any  title  to  the  rank  of  science,  and  Dalton's  explana- 
tion of  the  trade-winds  had  laid  the  foundation  for  a 
science  of  wind  dynamics  before  our  century  began. 
But  no  substantial  further  advance  in  this  direction  was 
effected  until  about  1827,  when  Heinrich  W.  Dove,  of 
Konigsberg,  afterwards  to  be  known  as  perhaps  the  fore- 
most meteorologist  of  his  generation,  included  the  winds 
among  the  subjects  of  his  elaborate  statistical  studies  in 
climatology. 

183 


THE   CENTURY'S   PROGRESS   IN   METEOROLOGY 

Dove  classified  the  winds  as  permanent,  periodical, 
and  variable.  His  great  discovery  was  that  all  winds, 
of  whatever  character,  and  not  merely  the  permanent 
winds,  come  under  the  influence  of  the  earth's  rotation 
in  such  a  way  as  to  be  deflected  from  their  course,  and 
hence  to  take  on  a  gyratory  motion — that,  in  short,  all 


A.  WHIRLWIND  IN   A  DUSTY  ROAD 

local  winds  are  minor  eddies  in  the  great  polar-equatori- 
al whirl,  and  tend  to  reproduce  in  miniature  the  char- 
acter of  that  vast  maelstrom.  For  the  first  time,  then, 
temporary  or  variable  winds  were  seen  to  lie  within  the 
province  of  law. 

A  generation   later,  Professor   William    Ferrel,  the 

183 


THE   STORY   OF   NINETEENTH-CENTURY  SCIENCE 

American  meteorologist,  who  had  been  led  to  take  up 
the  subject  by  a  perusal  of  Maury's  discourse  on  ocean 
winds,  formulated  a  general  mathematical  law,  to  the 
effect  that  any  body  moving  in  a  right  line  along  the 
surface  of  the  earth  in  any  direction  tends  to  have  its 
course  deflected,  owing  to  the  earth's  rotation,  to  the 
right  hand  in  the  northern  and  to  the  left  hand  in  the 
southern  hemispheres.  This  law  had  indeed  been  stated 
as  early  as  1835  by  the  French  physicist  Poisson,  but  no 
one  then  thought  of  it  as  other  than  a  mathematical 
curiosity  ;  its  true  significance  was  only  understood  after 
Professor  Ferrel  had  independently  rediscovered  it  (just  as 
Dalton  rediscovered  Hadley's  forgotten  law  of  the  trade- 
winds)  and  applied  it  to  the  motion  of  wind  currents. 

Then  it  became  clear  that  here  is  a  key  to  the  phe- 
nomena of  atmospheric  circulation,  from  the  great  polar- 
equatorial  maelstrom  which  manifests  itself  in  the  trade- 
winds,  to  the  most  circumscribed  riffle  which  is  an- 
nounced as  a  local  storm.  And  the  more  the  phenom- 
ena were  studied,  the  more  striking  seemed  the  parallel 
between  the  greater  maelstrom  and  these  lesser  eddies. 
Just  as  the  entire  atmospheric  mass  of  each  hemisphere 
is  seen,  when  viewed  as  a  whole,  to  be  carried  in  a  great 
whirl  about  the  pole  of  that  hemisphere,  so  the  local  dis- 
turbances within  this  great  tide  are  found  always  to 
take  the  form  of  whirls  about  a  local  storm-centre — 
which  storm-centre,  meantime,  is  carried  along  in  the 
major  current,  as  one  often  sees  a  little  whirlpool  in  the 
water  swept  along  with  the  main  current  of  the  stream. 
Sometimes,  indeed,  the  local  eddy,  caught  as  it  were  in 
an  ancillary  current  of  the  great  polar  stream,  is  de- 
flected from  its  normal  course  and  may  seem  to  travel 
against  the  stream ;  but  such  deviations  are  departures 

184 


TI1E  CENTURY'S   PROGRESS   IN   METEOROLOGY 

from  the  rule.     In  the  great  majority  of  cases,  for  ex- 
ample, in  the  north-temperate  zone,  a  storm-centre  (with 


WATEltSPOUTS  IN  MID- ATLANTIC 


its  attendant  local  whirl)  travels  to  the  northeast,  along 
the  main  current  of  the  anti-trade-wind,  of  which  it  is  a 

185 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

part;  and  though  exceptionally  its  course  may  be  to  the 
southeast  instead,  it  almost  never  departs  so  widely 
from  the  main  channel  as  to  progress  to  the  westward. 
Thus  it  is  that  storms  sweeping  over  the  United  States 
can  be  announced,  as  a  rule,  at  the  seaboard  in  advance 
of  their  coming  by  telegraphic  communication  from  the 
interior,  while  similar  storms  come  to  Europe  off  the 
ocean  unannounced.  Hence  the  more  practical  availa- 
bility of  the  forecasts  of  weather  bureaus  in  the  former 
country. 

But  these  local  whirls,  it  must  be  understood,  are  local 
only  in  a  very  general  sense  of  the  word,  inasmuch  as  a 
single  one  may  be  more  than  a  thousand  miles  in  diam- 
eter, and  a  small  one  is  two  or  three  hundred  miles 
across.  But  quite  without  regard  to  the  size  of  the 
whirl,  the  air  composing  it  conducts  itself  always  in  one 
of  two  ways.  It  never  whirls  in  concentric  circles ;  it 
always  either  rushes  in  towards  the  centre  in  a  de- 
scending spiral,  in  which  case  it  is  called  a  cyclone, 
or  it  spreads  out  from  the  centre  in  a  widening  spiral, 
in  which  case  it  is  called  an  anti-cyclone.  The  word 
cyclone  is  associated  in  popular  phraseology  with  a 
terrific  storm,  but  it  has  no  such  restriction  in  techni- 
cal usage.  A  gentle  zephyr  flowing  towards  a  "  storm- 
centre  "  is  just  as  much  a  cyclone  to  the  meteorologist 
as  is  the  whirl  constituting  a  West- Indian  hurricane. 
Indeed,  it  is  not  properly  the  wind  itself  that  is  called 
the  cyclone  in  either  case,  but  the  entire  system  of 
whirls  —  including  the  storm-centre  itself,  where  there 
may  be  no  wind  at  all. 

What,  then,  is  this  storm-centre  ?  Merely  an  area  of 
low  barometric  pressure — an  area  where  the  air  has  be- 
come lighter  than  the  air  of  surrounding  regions.  Under 

186 


..!.•     H     . 


OK   THK 

UNIVERSITY 


THE  CENTURY'S  PROGRESS  IN  METEOROLOGY 

influence  of  gravitation  the  air  seeks  its  level  just  as 
water  does;  so  the  heavy  air  comes  flowing  in  from  all 
sides  towards  the  low-pressure  area,  which  thus  becomes 
a  "storm-centre."  But  the  inrushing  currents  never 
come  straight  to  their  mark.  In  accordance  with  Fer- 
rers law,  they  are  deflected  to  the  right,  and  the  result, 
as  will  readily  be  seen,  must  be  a  vortex  current,  which 
whirls  always  in  one  direction  —  namely,  from  left  to 
right,  or  in  the  direction  opposite  to  that  of  the  hands 
of  a  watch  held  with  its  face  upward.  The  velocity  of 
the  cyclonic  currents  will  depend  largely  upon  the  dif- 
ference in  barometric  pressure  between  the  storm-centre 
and  the  confines  of  the  C37clone  system.  And  the  veloc- 
ity of  the  currents  will  determine  to  some  extent  the 
degree  of  deflection,  and  hence  the  exact  path  of  the 
descending  spiral  in  which  the  wind  approaches  the 
centre.  But  in  every  case  and  in  every  part  of  the 
cyclone  system  it  is  true,  as  Buys  Ballot's  famous  rule 
first  pointed  out,  that  a  person  standing  with  his  back 
to  the  wind  has  the  storm-centre  at  his  left. 

The  primary  cause  of  the  low  barometric  pressure 
which  marks  the  storm  -  centre  and  establishes  the 
cyclone  is  expansion  of  the  air  through  excess  of  tem- 
perature. The  heated  air,  rising  into  cold  upper  regions, 
has  a  portion  of  its  vapor  condensed  into  clouds,  and 
now  a  new  dynamic  factor  is  added,  for  each  particle  of 
vapor,  in  condensing,  gives  up  its  modicum  of  latent 
heat.  Each  pound  of  vapor  thus  liberates,  according  to 
Professor  Tyndall's  estimate,  enough  heat  to  melt  five 
pounds  of  cast  iron  ;  so  the  amount  given  out  where 
large  masses  of  cloud  are  forming  must  enormously  add 
to  the  convection  currents  of  the  air,  and  hence  to  the 
storm -developing  power  of  the  forming  cyclone.  In- 

189 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

deed,  one  school  of  meteorologists,  of  whom  Professor 
Espy  was  the  leader,  has  held  that  without  such  added 
increment  of  energy  constantly  augmenting  the  dynamic 
effects,  no  storm  could  long  continue  in  violent  action. 
And  it  is  doubted  whether  any  storm  could  ever  attain, 
much  less  continue,  the  terrific  force  of  that  most  dread- 
ed of  winds  of  temperate  zones,  the  tornado  —  a  storm 
which  obeys  all  the  laws  of  cyclones,  but  dffers  from 
ordinary  cyclones  in  having  a  vortex  core  only  a  few 
feet  or  yards  in  diameter  —  without  the  aid  of  those 
great  masses  of  condensing  vapor  which  always  accom- 
pany it  in  the  form  of  storm-clouds. 

The  anti-cyclone  simply  reverses  the  conditions  of  the 
cyclone.  Its  centre  is  an  area  of  high  pressure,  and  the 
air  rushes  out  from  it  in  all  directions  towards  surround- 
ing regions  of  low  pressure.  As  before,  all  parts  of  the 
current  will  be  deflected  towards  the  right,  and  the  re- 
sult, clearly,  is  a  whirl  opposite  in  direction  to  that  of 
the  cyclone.  But  here  there  is  a  tendency  to  dissipa- 
tion rather  than  to  concentration  of  energy,  hence,  con- 
sidered as  a  storm-generator,  the  anti-cyclone  is  of  rela- 
tive insignificance. 

In  particular  the  professional  meteorologist  who  con- 
ducts a  "  weather  bureau" — as,  for  example,  Sergeant 
Dunn,  of  the  United  States  signal-service  station  in  New 
York — is  so  preoccupied  with  the  observation  of  this 
phenomenon  that  cyclone-hunting  might  be  said  to  be 
his  chief  pursuit.  It  is  for  this  purpose,  in  the  main, 
that  government  weather  bureaus  or  signal-service  de- 
partments have  been  established  all  over  the  world. 
Their  chief  work  is  to  follow  up  cyclones,  with  the  aid 
of  telegraphic  reports,  mapping  their  course,  and  record- 
ing the  attendant  meteorological  conditions.  Their  so- 

190 


THE   CENTURY'S  PROGRESS   IN   METEOROLOGY 

called  predictions  or  forecasts  are  essentially  predica- 
tions, gaining  locally  the  effect  of  predictions  because 
the  telegraph  outstrips  the  wind. 

At  only  one  place  on  the  globe  has  it  been  possible  as 
yet  for  the  meteorologist  to  make  long-time  forecasts 
meriting  the  title  of  predictions.  This  is  in  the  middle 
Ganges  Yalley  of  northern  India.  In  this  country  the 
climatic  conditions  are  largely  dependent  upon  the  peri- 
odical winds  called  monsoons,  which  blow  steadily  land- 
ward from  April  to  October,  and  seaward  from  October 
to  April.  The  summer  monsoons  bring  the  all-essential 
rains ;  if  the}7  are  delayed  or  restricted  in  extent,  there 
will  be  drought  and  consequent  famine.  And  such  re- 
striction of  the  monsoon  is  likely  to  result  when  there 
has  been  an  unusually  deep  or  very  fate  snowfall  on  the 
Himalayas,  because  of  the  lowering  of  spring  tempera- 
ture by  the  melting  snow.  Thus  here  it  is  possible,  by 
observing  the  snowfall  in  the  mountains,  to  predict  with 
some  measure  of  success  the  average  rainfall  of  the  fol- 
lowing summer.  The  drought  of  1896,  with  the  conse- 
quent famine  and  plague  that  devastated  India  last  win- 
ter, was  thus  predicted  some  months  in  advance. 

This  is  the  greatest  present  triumph  of  practical  me- 
teorology. Nothing  like  it  is  yet  possible  anywhere  in 
temperate  zones.  But  no  one  can  say  what  may  not  be 
possible  in  times  to  come,  when  the  data  now  being 
gathered  all  over  the  world  shall  at  last  be  co-ordinated, 
classified,  and  made  the  basis  of  broad  inductions.  Me- 
teorology is  pre-eminently  a  science  of  the  future. 


CHAPTER  VI 
THE  CENTURY'S  PROGRESS  IN  PHYSIOS 


THERE  were  giants  abroad  in  the  world  of  science  in 
the  early  days  of  our  century.  Herschel,  Lagrange, 
and  Laplace ;  Cuvier,  Brongniart,  and  Lamarck ;  Hum- 
boldt,  Goethe,  Priestley — what  need  to  extend  the  list? 
— the  names  crowd  upon  us.  Bat  among  them  all  there 
was  no  taller  intellectual  figure  than  that  of  a  young 
Quaker  who  came  to  settle  in  London  and  practise  the 
profession  of  medicine  in  the  year  1801.  The  name  of 
this  young  aspirant  to  medical  honors  and  emoluments 
was  Thomas  Young.  He  came  fresh  from  professional 
studies  at  Edinburgh  and  on  the  Continent,  and  he  had 
the  theory  of  medicine  at  his  tongue's  end ;  yet  his 
medical  knowledge,  compared  with  the  mental  treasures 
of  his  capacious  intellect  as  a  whole,  was  but  as  a  drop 
of  water  in  the  ocean. 

For  it  chanced  that  this  young  Quaker  physician  was 
one  of  those  prodigies  who  come  but  few  times  in  a  cen- 
tury, and  the  full  list  of  whom  in  the  records  of  history 
could  be  told  on  one's  thumbs  and  fingers.  His  biogra- 
phers tell  us  things  about  him  that  read  like  the  most 
patent  fairy-tales.  As  a  mere  infant  in  arms  he  had 

192 


THE  CENTURY'S   PROGRESS   IN   PHYSICS 

been  able  to  read  fluently.  Before  his  fourth  birthday 
came  he  had  read  the  Bible  twice  through,  as  well  as 
Watts's  Hymns — poor  child  ! — and  when  seven  or  eight 
he  had  shown  a  propensity  to  absorb  languages  much 
as  other  children  absorb  nursery  tattle  and  Mother 
Goose  rhymes.  When  he  was  fourteen,  a  young  lady 
visiting  the  household  of  his  tutor  patronized  the  pretty 
boy  by  asking  to  see  a  specimen  of  his  penmanship. 
The  pretty  boy  complied  readily  enough,  and  mildly  re- 
buked his  interrogator  by  rapidly  writing  some  sen- 
tences for  her  in  fourteen  languages,  including  such  as 
Arabian,  Persian,  and  Ethiopic. 

Meantime  languages  had  been  but  an  incident  in  the 
education  of  the  lad.  He  seems  to  have  entered  every 
available  field  of  thought — mathematics,  physics,  bot- 
any, literature,  music,  painting,  languages,  philosophy, 
archaeology,  and  so  on  to  tiresome  lengths — and  once  he 
had  entered  any  field  he  seldom  turned  aside  until  he 
had  reached  the  confines  of  the  subject  as  then  known, 
and  added  something  new  from  the  recesses  of  his  own 
genius.  He  was  as  versatile  as  Priestley,  as  profound 
as  Newton  himself.  He  had  the  range  of  a  mere  dilet- 
tante, but  everywhere  the  full  grasp  of  the  master.  He 
took  early  for  his  motto  the  saying  that  what  one  man 
has  done,  another  man  may  do.  Granting  that  the 
other  man  has  the  brain  of  a  Thomas  Young,  it  is  a  true 
motto. 

Such  then  was  the  young  Quaker  who  came  to  London 
to  follow  out  the  humdrum  life  of  a  practitioner  of  medi- 
cine in  the  year  1801.  But  incidentally  the  young  pl^si- 
cian  was  prevailed  upon  to  occupy  the  interims  of  early 
practice  by  fulfilling  the  duties  of  the  chair  of  Natural  Phi- 
losophy at  the  Royal  Institution,  which  Count  Rumford 
H  193 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

had  founded,  and  of  which  Davy  was  then  Professor  of 
Chemistry — the  institution  whose  glories  have  been  per- 
petuated by  such  names  as  Faraday  and  Tyndall,  and 
which  the  Briton  of  to-day  speaks  of  as  the  "  Pantheon 
of  Science."  Here  it  was  that  Thomas  Young  made 
those  studies  which  have  insured  him  a  niche  in  the 
temple  of  fame  not  far  removed  from  that  of  Isaac 
Newton. 

As  early  as  1793,  when  he  was  only  twent}7",  Young 
had  begun  to  communicate  papers  to  the  Royal  Society 
of  London,  which  were  adjudged  worthy  to  be  printed 
in  full  in  the  Philosophical  Transactions;  so  it  is  not 
strange  that  he  should  have  been  asked  to  deliver  the 
Bakerian  lecture  before  that  learned  body  the  very  first 
year  after  he  came  to  London.  The  lecture  was  deliv- 
ered November  12, 1801.  Its  subject  was  "  The  Theory 
of  Light  and  Colors,"  and  its  reading  marks  an  epoch  in 
physical  science ;  for  here  was  brought  forward  for  the 
first  time  convincing  proof  of  that  undulatory  theory  of 
light  with  which  every  student  of  modern  physics  is  fa- 
miliar— the  theory  which  holds  that  light  is  not  a  cor- 
poreal entity,  but  a  mere  pulsation  in  the  substance  of 
an  all-pervading  ether,  just  as  sound  is  a  pulsation  in  the 
air,  or  in  liquids  or  solids 

Young  had,  indeed,  advocated  this  theory  at  an  earli- 
er date,  but  it  was  not  until  1801  that  he  hit  upon  the 
idea  which  enabled  him  to  bring  it  to  anything  ap- 
proaching a  demonstration.  It  was  while  pondering 
over  the  familiar  but  puzzling  phenomena  of  colored 
rings  into  which  white  light  is  broken  when  reflected 
from  thin  films — Newton's  rings,  so  called — that  an  ex- 
planation occurred  to  him  which  at  once  put  the  entire 
undulatory  theory  on  a  new  footing.  "With  that  sagac- 

194 


THOMAS  YOUNG 

From  Peacock's  Life  of  Young,  by  permission  of  John  Murray,  Publisher,  London 


THE   CENTURY'S    PROGRESS   IN   PHYSICS 

ity  of  insight  which  we  call  genius,  he  saw  of  a  sudden 
that  the  phenomena  could  be  explained  by  supposing 
that  when  rays  of  light  fall  on  a  thin  glass,  part  of  the 
rays  being  reflected  from  the  upper  surface,  other  rays, 
reflected  from  the  lower  surface,  might  be  so  retarded 
in  their  course  through  the  glass  that  the  two  sets  would 
interfere  with  one  another,  the  forward  pulsation  of  one 
ray  corresponding  to  the  backward  pulsation  of  another, 
thus  quite  neutralizing  the  effect.  Some  of  the  com- 
ponent pulsations  of  the  light  being  thus  effaced  by 
mutual  interference,  the  remaining  rays  would  no  longer 
give  the  optical  effect  of  white  light;  hence  the  puz- 
zling colors. 

By  following  up  this  clew  with  mathematical  preci- 
sion, measuring  the  exact  thickness  of  the  plate  and  the 
space  between  the  different  rings  of  color,  Young  was 
able  to  show  mathematically  what  must  be  the  length 
of  pulsation  for  each  of  the  different  colors  of  the  spec- 
trum. He  estimated  that  the  undulations  of  red  light, 
at  the  extreme  lower  end  of  the  visible  spectrum,  must 
number  about  37,640  to  the  inch,  and  pass  any  given 
spot  at  a  rate  of  463  millions  of  millions  of  undulations 
in  a  second,  while  the  extreme  violet  numbers  59,750 
undulations  to  the  inch,  or  735  millions  of  millions  to 
the  second. 

Young  similarly  examined  the  colors  that  are  pro- 
duced by  scratches  on  a  smooth  surface,  in  particular 
testing  the  light  from  "  Mr.  Coventry's  exquisite  mi- 
crometers," which  consist  of  lines  scratched  on  glass  at 
measured  intervals.  These  microscopic  tests  brought 
the  same  results  as  the  other  experiments.  The  colors 
were  produced  at  certain  definite  and  measurable  angles, 
and  the  theory  of  interference  of  undulations  explained 

197 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

them  perfectly,  while,  as  Young  affirmed  with  confi- 
dence, no  other  theory  hitherto  advanced  could  explain 
them  at  all.  Taking  all  the  evidence  together,  Young 
declared  that  he  considered  the  argument  he  had  set 
forth  in  favor  of  the  undulatory  theory  of  light  to  be 
"  sufficient  and  decisive." 

This  doctrine  of  interference  of  undulations  was  the 
absolutely  novel  part  of  Young's  theory.  The  all- 
compassing  genius  of  Robert  Hooke  had,  indeed,  very 
nearly  apprehended  it  more  than  a  century  before,  as 
Young  himself  points  out,  but  no  one  else  had  so  much 
as  vaguely  conceived  it ;  and  even  with  the  sagacious 
Hooke  it  was  only  a  happy  guess,  never  distinctly  out- 
lined in  his  own  mind,  and  utterly  ignored  by  all  others. 
Young  did  not  know  of  Hooke's  guess  until  he  himself 
had  fully  formulated  the  theory,  but  he  hastened  then 
to  give  his  predecessor  all  the  credit  that  could  possibly 
be  adjudged  his  due  by  the  most  disinterested  observer. 
To  Hooke's  contemporary,  Huyghens,  who  was  the  orig- 
inator of  the  general  doctrine  of  undulation  as  the  ex- 
planation of  light,  Young  renders  full  justice  also.  For 
himself  he  claims  only  the  merit  of  having  demonstrated 
the  theory  which  these  and  a  few  others  of  his  prede- 
cessors had  advocated  without  full  proof. 

The  following  year  Dr.  Young  detailed  before  the 
Eoyal  Society  other  experiments,  which  threw  addi- 
tional light  on  the  doctrine  of  interference;  and  in  1803 
he  cited  still  others,  which,  he  affirmed,  brought  the 
doctrine  to  complete  demonstration.  In  applying  this 
demonstration  to  the  general  theory  of  light,  he  made 
the  striking  suggestion  that  "  the  luminiferous  ether 
pervades  the  substance  of  all  material  bodies  with  little 
or  no  resistance,  as  freely,  perhaps,  as  the  wind  passes 

198 


THE   CENTURY'S   PROGRESS   IN  PHYSICS 

through  a  grove  of  trees."  He  asserted  his  belief  also 
that  the  chemical  rays  which  Hitter  had  discovered 
beyond  the  violet  end  of  the  visible  spectrum  are  but 
still  more  rapid  undulations  of  the  same  character  as 
those  which  produce  light.  In  his  earlier  lecture  he 
had  affirmed  a  like  affinity  between  the  light  rays  and 
the  rays  of  radiant  heat  which  Herschel  detected  below 
the  red  end  of  the  spectrum,  suggesting  that  "  light 
differs  from  heat  only  in  the  frequency  of  its  undu- 
lations or  vibrations  —  those  undulations  which  are 
within  certain  limits  with  respect  to  frequency  affect- 
ing the  optic  nerve  and  constituting  light,  and  those 
which  are  slower  and  probably  stronger  constituting 
heat  only."  From  the  very  outset  he  had  recognized 
the  affinity  between  sound  and  light ;  indeed,  it  had 
been  this  affinity  that  led  him  on  to  an  appreciation 
of  the  undulatory  theory  of  light. 

But  while  all  these  affinities  seemed  so  clear  to  the 
great  co-ordinating  brain  of  Young,  they  made  no  such 
impression  on  the  minds  of  his  contemporaries.  The 
immateriality  of  light  had  been  substantially  demon- 
strated, but  practically  no  one  save  its  author  accepted 
'the  demonstration.  Newton's  doctrine  of  the  emission 
of  corpuscles  was  too  firmly  rooted  to  be  readily  dis- 
lodged, and  Dr.  Young  had  too  many  other  interests  to 
continue  the  assault  unceasingly.  He  occasionally  wrote 
something  touching  on  his  theory,  mostly  papers  con- 
tributed to  the  Quarterly  Review  and  similar  period- 
icals, anonymously  or  under  a  pseudonym,  for  he  had 
conceived  the  notion  that  too  great  conspicuousness  in 
fields  outside  of  medicine  would  injure  his  practice  as  a 
physician.  His  views  regarding  light  (including  the 
original  papers  from  the  Philosophical  Transactions  of 

199 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

the  Royal  Society]  were  again  given  publicity  in  full  in 
his  celebrated  volume  on  natural  philosophy,  consisting 
in  part  of  his  lectures  before  the  Royal  Institution,  pub- 
lished in  1807;  but  even  then  they  failed  to  bring  con- 
viction to  the  philosophic  world.  Indeed,  they  did  not 
even  arouse  a  controversial  spirit,  as  his  first  papers  had 
done. 

So  it  chanced  that  when,  in  1815,  a  young  French 
military  engineer,  named  Augustin  Jean  Fresnel,  re- 
turning from  the  Napoleonic  wars,  became  interested  in 
the  phenomena  of  light,  and  made  some  experiments 
concerning  diffraction,  which  seemed  to  him  to  contro- 
vert the  accepted  notions  of  the  materiality  of  light,  he 
was  quite  unaware  that  his  experiments  had  been  an- 
ticipated by  a  philosopher  across  the  Channel.  He 
communicated  his  experiments  and  results  to  the  French 
Institute,  supposing  them  to  be  absolutely  novel.  That 
body  referred  them  to  a  committee,  of  which,  as  good 
fortune  would  have  it,  the  dominating  member  was 
Dominique  Francois  Arago,  a  man  as  versatile  as  Young 
himself,  and  hardly  less  profound,  if  perhaps  not  quite  so 
original.  Arago  at  once  recognized  the  merit  of  Fres- 
nel's  work,  and  soon  became  a  convert  to  the  theory. 
He  told  Fresnel  that  Young  had  anticipated  him  as  re- 
gards the  general  theory,  but  that  much  remained  to  be 
done,  and  he  offered  to  associate  himself  with  Fresnel 
in  prosecuting  the  investigation.  Fresnel  was  not  a 
little  dashed  to  learn  that  his  original  ideas  had  been 
worked  out  by  another  while  he  was  a  lad,  but  he 
bowed  gracefully  to  the  situation,  and  went  ahead  with 
unabated  zeal. 

The  championship  of  Arago  insured  the  undulatory 
theory  a  hearing  before  the  French  Institute,  but  by  no 

200 


HAN'S  CHRISTIAN   OERSTED 


DOMINIQUE   FRANCOIS   ARAGO 


AOGPSTIN   JEAN   FRESNEL 


JAMES  CLERK  MAXWELL 


OK    XHK 

UNIVERSITY 


THE   CENTURY'S   PROGRESS   IN   PHYSICS 

means  sufficed  to  bring  about  its  general  acceptance.  On 
the  contrary,  a  bitter  feud  ensued,  in  which  Arago  was 
opposed  by  the  "Jupiter  Olyrapius  of  the  Academy," 
Laplace,  by  the  only  less  famous  Poisson,  and  by  the 
younger  but  hardly  less  able  Biot.  So  bitterly  raged  the 
feud  that  a  life-long  friendship  between  Arago  and  Biot 
was  ruptured  forever.  The  opposition  managed  to  delay 
the  publication  of  Fresnel's  papers,  but  Arago  continued 
to  fight  with  his  customary  enthusiasm  and  pertinacity, 
and  at  last,  in  1823,  the  Academy  yielded,  and  voted 
Fresnel  into  its  ranks,  thus  implicitly  admitting  the 
value  of  his  work. 

It  is  a  humiliating  thought  that  such  controversies  as 
this  must  mar  the  progress  of  scientific  truth  ;  but  fort- 
unately the  story  of  the  introduction  of  the  undulatory 
theory  has  a  more  pleasant  side.  Three  men,  great  both 
in  character  and  in  intellect,  were  concerned  in  pressing 
its  claims — Young,  Fresnel  and  Arago  —  and  the  rela- 
tions of  these  men  form  a  picture  unmarred  by  any 
of  those  petty  jealousies  that  so  often  dim  the  lustre 
of  great  names.  Fresnel  freely  acknowledged  Young's 
prioritjr  so  soon  as  his  attention  was  called  to  it ;  and 
Young  applauded  the  work  of  the  Frenchman,  and 
aided  with  his  counsel  in  the  application  of  the  undula- 
tory theory  to  the  problems  of  polarization  of  light, 
which  still  demanded  explanation,  and  which  Fresnel's 
fertility  of  experimental  resource  and  profundity  of 
mathematical  insight  sufficed  in  the  end  to  conquer. 

After  Fresnel's  admission  to  the  Institute  in  1823  the 
opposition  weakened,  and  gradually  the  philosophers 
came  to  realize  the  merits  of  a  theory  which  Young 
had  vainly  called  to  their  attention  a  full  quarter- 
century  before.  Now,  thanks  largely  to  Arago,  both 

303 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

Young  and  Fresnel  received  their  full  meed  of  apprecia- 
tion. Fresnel  was  given  the  Rum  ford  medal  of  the 
Royal  Society  of  England  in  1825,  and  chosen  one  of  the 
foreign  members  of  the  Society  t\vo  years  later,  while 
Young  in  turn  was  elected  one  of  the  eight  foreign 
members  of  the  French  Academy.  As  a  fitting  culmi- 
nation of  the  chapter  of  felicities  between  the  three 
friends,  it  fell  to  the  lot  of  Young,  as  Foreign  Secretary 
of  the  Royal  Society,  to  notify  Fresnel  of  the  honors 
shown  him  by  England's  representative  body  of  sci- 
entists; while  Arago,  as  Perpetual  Secretary  of  the 
French  Institute,  conveyed  to  Young  in  the  same  year 
the  notification  that  he  had  been  similarly  honored  by 
the  savants  of  France. 

A  few  months  later  Fresnel  was  dead,  and  Young 
survived  him  only  two  years.  Both  died  premature- 
ly ;  but  their  great  work  was  done,  and  the  world  will 
remember  always  and  link  together  these  two  names  in 
connection  with  a  theory  which  in  its  implications  and 
importance  ranks  little  below  the  theory  of  universal 
gravitation. 

ii 

The  full  importance  of  Young's  studies  of  light  might 
perhaps  have  gained  earlier  recognition  had  it  not 
chanced  that,  at  the  time  when  they  were  made,  the 
attention  of  the  philosophic  world  was  turned  with  the 
fixity  and  fascination  of  a  hypnotic  stare  upon  another 
field,  which  for  a  time  brooked  no  rival.  How  could 
the  old  familiar  phenomenon  light  interest  any  one 
when  the  new  agent  galvanism  was  in  view?  As  well 
ask  one  to  fix  attention  on  a  star  while  a  meteorite 
blazes  across  the  sky. 

204 


THE  CENTURY'S   PROGRESS   IN   PHYSICS 

The  question  of  the  hour  was  whether  in  galvanism 
the  world  had  to  do  with  a  new  force,  or  whether  it  is 
identical  with  electricity,  masking  under  a  new  form. 
Very  early  in  the  century  the  profound,  if  rather  cap- 
tious, Dr.  Wollaston  made  experiments  which  seemed  to 
show  that  the  two  are  identical ;  and  by  1807  Dr.  Young 
could  write  in  his  published  lectures  :  "  The  identity  of 
the  general  causes  of  electrical  and  of  galvanic  effects  is 
now  doubted  by  few."  To  be  entirely  accurate,  he 
should  have  added,  "  by  few  of  the  leaders  of  scientific 
thought,"  for  the  lesser  lights  were  by  no  means  so  fully 
agreed  as  the  sentence  cited  might  seem  to  imply. 

But  meantime  an  even  more  striking  affinity  had  been 
found  for  the  new  agent  galvanism.  From  the  first  it 
had  been  the  chemists  rather  than  the  natural  philoso- 
phers— the  word  physicist  was  not  then  in  vogue — who 
had  chiefly  experimented  with  Volta's  battery  ;  and  the 
acute  mind  of  Humphry  Davy  at  once  recognized  the 
close  relationship  between  chemical  decomposition  and 
the  appearance  of  the  new  "  imponderable."  The  great 
Swedish  chemist  Berzelius  also  had  an  inkling  of  the 
same  thing.  But  it  was  Davy  who  first  gave  the 
thought  full  expression,  in  a  Bakerian  lecture  before 
the  Royal  Society  in  1806 — the  lecture  which  gained 
him  not  only  the  plaudits  of  his  own  countrymen,  but 
the  Napoleonic  prize  of  the  French  Academy  at  a  time 
when  the  political  bodies  of  the  two  countries  were  in 
the  midst  of  a  sanguinary  war.  "  Science  knows  no 
country,"  said  the  young  Englishman,  in  accepting  the 
French  testimonial,  against  the  wishes  of  some  of  the 
more  narrow-minded  of  his  friends.  "  If  the  two  coun- 
tries or  governments  are  at  war,  the  men  of  science  are 
not.  That  would,  indeed,  be  a  civil  war  of  the  worst 

205 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

description.  We  should  rather,  through  the  instru- 
mentality of  men  of  science,  soften  the  asperities  of 
national  hostility." 

Here  it  was  that  Davy  explicitly  stated  his  belief 
that  "chemical  and  electrical  attraction  are  produced 
by  the  same  cause,  acting  in  one  case  on  particles,  in 
the  other  on  masses,"  and  that  "  the  same  property, 
under  different  modifications,  is  the  cause  of  all  the 
phenomena  exhibited  by  different  voltaic  combinations." 
The  phenomena  of  galvanism  were  thus  linked  with 
chemical  action  on  the  one  hand,  and  with  frictional 
electricit}7  on  the  other,  in  the  first  decade  of  the  cen- 
tury, showing  that  electricity  is  by  no  means  the  iso- 
lated "fluid''  that  it  had  been  thought.  But  there  the 
matter  rested  for  another  decade.  The  imaginative 
Davy,  whose  penetrative  genius  must  have  carried  him 
further  had  it  not  been  diverted,  became  more  and  more 
absorbed  in  the  chemical  side  of  the  problem  ;  and 
Young,  having  severed  his  connection  with  the  Koyal 
Institution,  was  devoting  himself  to  developing  his  med- 
ical practice,  and  in  intervals  of  duty  to  deciphering 
Egyptian  hieroglyphics.  Parenthetically  it  may  be 
added  that  Young  was  far  too  much  in  advance  of  his 
time  to  make  a  great  success  as  a  practitioner  (people 
demand  sophistry  rather  than  philosophy  of  their  fam- 
ily physician),  but  that  his  success  with  the  hiero- 
glyphics was  no  less  novel  and  epoch-making  than  his 
work  in  philosophy. 

For  a  time  no  master-generalizer  came  to  take  the  place 
of  these  men  in  the  study  of  the  "  imponderables  "  as  such, 
and  the  phenomena  of  electricity  occupied  an  isolated  cor- 
ner in  the  realm  of  science,  linked,  as  has  been  said  rather 
to  chemistry  than  to  the  field  we  now  term  physics. 

206 


THE   CENTURY'S   PROGRESS   IN   PHYSICS 

But  in  the  year  1819  there  flashed  before  the  philo- 
sophic world,  like  lightning  from  a  clear  sky,  the  report 
that  Hans  Christian  Oersted,  the  Danish  philosopher, 
had  discovered  that  the  magnetic  needle  may  be  deflect- 
ed by  the  passage  near  it  of  a  current  of  electricity. 
The  experiment  was  repeated  everywhere.  Its  validity 
was  beyond  question,  its  importance  beyond  estimate. 
Many  men  had  vaguely  dreamed  that  there  might  be 
some  connection  between  electricity  and  magnetism — 
chiefly  because  each  shows  phenomena  of  seeming  at- 
traction and  repulsion — but  here  was  the  first  experi- 
mental evidence  that  any  such  connection  actually  ex- 
ists. The  wandering  eye  of  science  was  recalled  to  elec- 
tricity as  suddenly  and  as  irresistibly  as  it  had  been  in 
1800  by  the  discovery  of  the  voltaic  pile.  But  now  it 
was  the  physical  rather  than  the  chemical  side  of  the 
subject  that  chiefly  demanded  attention. 

At  once  Andre  Marie  Ampere,  whom  the  French  love 
to  call  the  Newton  of  electricity,  appreciated  the  far- 
reaching  importance  of  the  newly  disclosed  relationship, 
and,  combining  mathematical  and  experimental  studies, 
showed  how  close  is  the  link  between  electricity  and 
magnetism,  and  suggested  the  possibility  of  signalling 
at  a  distance  by  means  of  electric  wires  associated  with 
magnetic  needles.  Gauss,  the  great  mathematician,  and 
Weber,  the  physicist,  put  this  idea  to  a  practical  test  by 
communicating  with  one  another  at  a  distance  of  sev- 
eral roods,  in  Gottingen,  long  before  "  practical "  teleg- 
raphy grew  out  of  Oersted's  discovery. 

A  new  impetus  thus  being  given  to  the  investigators, 
an  epoch  of  electrical  discovery  naturally  followed.  For 
a  time  interest  centred  on  the  French  investigators,  in 
particular  upon  the  experiments  of  the  ever-receptive 

207 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

Arago,  who  discovered  in  1825  that  magnets  may  be 
produced  at  will  by  electrical  induction.  But  about 
1830  the  scene  shifted  to  London  ;  for  then  the  protege 
of  Davy,  and  his  successor  in  the  Royal  Institution, 
Michael  Faraday,  the  "  man  who  added  to  the  powers 
of  his  intellect  all  the  graces  of  the  human  heart."  began 
that  series  of  electrical  experiments  at  the  Royal  Insti- 
tution which  were  destined  to  attract  the  dazed  atten- 
tion of  the  philosophic  world,  and  stamp  their  originator 
as  "  the  greatest  experimental  philosopher  the  world 
has  ever  seen."  Nor  does  the  rank  of  prince  of  experi- 
menters do  Faraday  full  justice,  for  he  was  far  more 
than  a  mere  experimenter.  He  had  not,  perhaps,  quite 
the  intuitive  insight  of  Davy,  and  he  utterly  lacked  the 
profound  mathematical  training  of  Young.  None  the 
less  was  he  a  man  who  could  dream  dreams  on  occasion, 
and,  as  Maxwell  has  insisted,  think  in  mathematical 
channels  if  not  with  technical  symbols.  Only  his  wagon 
must  always  traverse  earth  though  hitched  to  a  star. 
His  dreams  guided  him  onward,  but  ever  the  hand  of 
experiment  kept  check  over  the  dreams. 

It  was  in  1831  that  Faraday  opened  up  the  field  of 
magneto-electricity.  Reversing  the  experiments  of  his 
predecessors,  who  had  found  that  electric  currents  may 
generate  magnetism,  he  showed  that  magnets  have 
power  under  certain  circumstances  to  generate  electric- 
ity ;  he  proved,  indeed,  the  interconvertibility  of  elec- 
tricity and  magnetism.  Then  he  showed  that  all  bodies 
are  more  or  less  subject  to  the  influence  of  magnetism, 
and  that  even  light  may  be  affected  by  magnetism  as  to 
its  phenomena  of  polarization.  He  satisfied  himself 
completely  of  the  true  identity  of  all  the  various  forms 
of  electricity,  and  of  the  convertibility  of  electricity  and 

208 


THE  CENTURY'S   PROGRESS   IN   PHYSICS 

chemical  action.  Thus  he  linked  together  light,  chemi- 
cal affinity,  magnetism,  and  electricity.  And,  moreover, 
he  knew  full  well  that  no  one  of  these  can  be  produced 
in  indefinite  supply  from  another.  Nowhere,  he  says, 
"is  there  a  pure  creation  or  production  of  power  with- 
out a  corresponding  exhaustion  of  something  to  supply 
it." 

When  Faraday  wrote  those  words  in  1840  he  was 
treading  on  the  very  heels  of  a  greater  generalization 
than  any  which  he  actually  formulated  ;  nay,  he  had  it 
fairly  within  his  reach.  He  saw  a  great  truth  without 
fully  realizing  its  import;  it  was  left  for  others,  ap- 
proaching the  same  truth  along  another  path,  to  point 
out  its  full  significance. 

in 

The  great  generalization  which  Faraday  so  narrowly 
missed  is  the  truth  which  since  then  has  become  familiar 
as  the  doctrine  of  the  conservation  of  energy — the  law 
that  in  transforming  energy  from  one  condition  to  an- 
other we  can  never  secure  more  than  an  equivalent 
quantity;  that,  in  short,  "to  create  or  annihilate  ener- 
gy is  as  impossible  as  to  create  or  annihilate  matter; 
and  that  all  the  phenomena  of  the  material  universe 
consist  in  transformations  of  energy  alone."  Some  phi- 
losophers think  this  the  greatest  generalization  ever 
conceived  by  the  mind  of  man.  Be  that  as  it  may,  it  is 
surely  one  of  the  great  intellectual  landmarks  of  our 
century.  It  stands  apart,  so  stupendous  and  so  far- 
reaching  in  its  implications  that  the  generation  which 
first  saw  the  law  developed  could  little  appreciate  it ; 
only  now,  through  the  vista  of  half  a  century,  do  we 
begin  to  see  it  in  its  true  proportions. 
o  209 


THE  STORY  OF  NINETEENTfl-CRNTUKY  SCIENCE 

A  vast  generalization  such  as  this  is  never  a  mush- 
room growth,  nor  does  it  usually  spring  full  grown  from 
the  mind  of  any  single  man.  Always  a  number  of 
minds  are  very  near  a  truth  before  any  one  mind  fully 
grasps  it.  Pre-eminently  true  is  this  of  the  doctrine  of 
conservation  of  energy.  Not  Faraday  alone,  but  half  a 
dozen  different  men  had  an  inkling  of  it  before  it  gained 
full  expression;  indeed,  every  man  who  advocated  the 
undulatory  theory  of  light  and  heat  was  verging  towards 
the  goal.  The  doctrine  of  Young  and  Fresnel  was  as  a 
highway  leading  surely  on  to  the  wide  plain  of  conser- 
vation. The  phenomena  of  electro-magnetism  furnished 
another  such  highway.  But  there  was  yet  another  road 
which  led  just  as  surely  and  even  more  readily  to  the 
same  goal.  This  was  the  road  furnished  by  the  phe- 
nomena of  heat,  and  the  men  who  travelled  it  were  des- 
tined to  outstrip  their  fello w- workers  ;  though,  as  we 
have  seen,  wayfarers  on  other  roads  were  within  hailing 
distance  when  the  leaders  passed  the  mark. 

In  order  to  do  even  approximate  justice  to  the  men 
who  entered  into  the  great  achievement,  we  must  recall 
that  just  at  the  close  of  the  last  century  Count  Rumford 
and  Humphry  Davy  independently  showed  that  labor 
may  be  transformed  into  heat ;  and  correctly  interpreted 
this  fact  as  meaning  the  transformation  of  molar  into 
molecular  motion.  We  can  hardly  doubt  that  each  of 
these  men  of  genius  realized,  vaguely,  at  any  rate,  that 
there  must  be  a  'close  correspondence  between  the 
amount  of  the  molar  and  the  molecular  motions;  hence 
that  each  of  them  was  in  sight  of  the  law  of  the  me- 
chanical equivalent  of  heat.  But  neither  of  them  quite 
grasped  or  explicitly  stated  what  each  must  vaguely 
have  seen ;  and  for  just  a  quarter  of  a  century  no  one 

210 


MICHAEL  FARADAY 


THE   CENTURY'S   PROGRESS   IN   PHYSICS 

else  even  came  abreast  their  line  of  thought,  let  alone 
passing  it. 

But  then,  in  1824,  a  French  philosopher,  Sadi  Carnot, 
caught  step  with  the  great  Englishmen,  and  took  a  long 
leap  ahead  by  explicitly  stating  his  belief  that  a  definite 
quantity  of  work  could  be  transformed  into  a  definite 
quantity  of  heat,  no  more,  no  less.  Carnot  did  not,  in- 
deed, reach  the  clear  view  of  his  predecessors  as  to  the 
nature  of  heat,  for  he  still  thought  it  a  form  of  "  impon- 
derable" fluid;  but  he  reasoned  none  the  less  clearly  as 
to  its  mutual  convertibility  with  mechanical  work.  But 
important  as  his  conclusions  seem  now  that  we  look 
back  upon  them  with  clearer  vision,  they  made  no  im- 
pression whatever  upon  his  contemporaries.  Carnot's 
work  in  this  line  was  an  isolated  phenomenon  of  histori- 
cal interest,  but  it  did  not  enter  into  the  scheme  of  the 
completed  narrative  in  any  such  way  as  did  the  work  of 
Kumford  and  Davy. 

The  man  who  really  took  up  the  broken  thread  where 
Rumford  and  Davy  had  dropped  it,  and  wove  it  into  a 
completed  texture,  came  upon  the  scene  in  1840.  His 
home  was  in  Manchester,  England  ;  his  occupation  that 
of  a  manufacturer.  He  was  a  friend  and  pupil  of  the 
great  Dr.  Dalton.  His  name  was  James  Prescott  Joule. 
When  posterity  has  done  its  final  juggling  with  the 
names  of  our  century,  it  is  not  unlikely  that  the  name  of 
this  Manchester  philosopher  will  be  a  household  Word 
like  the  names  of  Aristotle,  Copernicus,  and  Newton. 

For  Joule's  work  it  was,  done  in  the  fifth  decade  of  our 
century,  which  demonstrated  beyond  all  cavil  that  there 
is  a  precise  and  absolute  equivalence  between  mechani- 
cal work  and  heat ;  that  whatever  the  form  of  mani- 
festation of  molar  motion,  it  can  generate  a  definite  and 

213 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

measurable  amount  of  heat,  and  no  more.  Joule  found, 
for  example,  that  at  the  sea-level  in  Manchester  a  pound 
weight  falling  through  seven  hundred  and  seventy-two 
feet  could  generate  enough  heat  to  raise  the  temperature 
of  a  pound  of  water  one  degree  Fahrenheit.  There  was 
nothing  haphazard,  nothing  accidental,  about  this  ;  it 
bore  the  stamp  of  unalterable  law.  And  Joule  himself 
saw,  what  others  in  time  were  made  to  see,  that  this 
truth  is  merely  a  particular  case  within  a  more  general 
law.  If  heat  cannot  be  in  any  sense  created,  but  only 
made  manifest  as  a  transformation  of  another  kind  of 
motion,  then  must  not  the  same  thing  be  true  of  all 
those  other  forms  of  "force" — light,  electricity,  magnet- 
ism— which  had  been  shown  to  be  so  closely  associated, 
so  mutually  convertible,  with  heat?  All  analogy  seemed 
to  urge  the  truth  of  this  inference  ;  all  experiment  tend- 
ed to  confirm  it.  The  law  of  the  mechanical  equivalent 
of  heat  then  became  the  main  corner-stone  of  the  greater 
law  of  the  conservation  of  energy. 

But  while  this  citation  is  fresh  in  mind,  we  must  turn 
our  attention  with  all  haste  to  a  country  across  the 
Channel — to  Denmark,  in  short— and  learn  that  even  as 
Joule  experimented  with  the  transformation  of  heat,  a 
philosopher  of  Copenhagen,  Colding  by  name,  had  hit 
upon  the  same  idea,  and  carried  it  far  towards  a  demon- 
stration. And  then,  without  pausing,  we  must  shift  yet 
again,  this  time  to  Germany,  and  consider  the  work  of 
three  other  men,  who  independently  were  on  the  track 
of  the  same  truth,  and  two  of  whom,  it  must  be  admit- 
ted, reached  it  earlier  than  either  Joule  or  Colding, 
if  neither  brought  it  to  quite  so  clear  a  demonstra- 
tion. The  names  of  these  three  Germans  are  Mohr, 
Mayer,  and  Helmholtz.  Their  share  in  establishing 

214 


THE   CENTURY'S   PROGRESS   IN   PHYSICS 

the  great  doctrine  of  conservation  must  now  claim  our 
attention. 

As  to  Karl  Friedrich  Mohr,  it  may  be  said  that  his 
statement  of  the  doctrine  preceded  that  of  any  of  his 
fellows,  yet  that  otherwise  it  was  perhaps  least  impor- 
tant. In  1837  this  thoughtful  German  had  grasped  the 
main  truth,  and  given  it  expression  in  an  article  pub- 
lished in  the  Zeitschrift  fur  Physik,  etc.  But  the  article 
attracted  no  attention  whatever,  even  from  Mohr's  own 
countrymen.  Still,  Mohr's  title  to  rank  as  one  who 
independently  conceived  the  great  truth,  and  perhaps 
first  conceived  it  before  any  other  man  in  the  world 
saw  it  as  clearly,  even  though  he  did  not  demonstrate 
its  validity,  is  not  to  be  disputed. 

It  was  just  five  years  later,  in  1842,  that  Dr.  Julius 
Robert  Mayer,  practising  physician  in  the  little  German 
town  of  Heilbronn,  published  a  paper  in  Liebig's  Annalen 
on  "The  Forces  of  Inorganic  Nature,"  in  which  not 
merely  the  mechanical  theory  of  heat,  but  the  entire 
doctrine  of  the  conservation  of  energy,  is  explicitly  if 
briefly  stated.  Two  years  earlier  Dr.  Mayer,  while 
surgeon  to  a  Dutch  India  vessel  cruising  in  the  tropics, 
had  observed  that  the  venous  blood  of  a  patient  seemed 
redder  than  venous  blood  usually  is  observed  to  be  in 
temperate  climates.  He  pondered  over  this  seemingly 
insignificant  fact,  and  at  last  reached  the  conclusion 
that  the  cause  must  be  the  lesser  amount  of  oxidation 
required  to  keep  up  the  body  temperature  in  the  tropics. 
Led  by  this  reflection  to  consider  the  body  as  a  machine 
dependent  on  outside  forces  for  its  capacity  to  act,  he 
passed  on  into  a  novel  realm  of  thought,  which  brought 
him  at  last  to  independent  discovery  of  the  mechanical 
theory  of  heat,  and  to  the  first  full  and  comprehensive 

315 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

appreciation  of  the  great  law  of  conservation.  Blood- 
letting, the  modern  physician  holds,  was  a  practice  of 
very  doubtful  benefit,  as  a  rule,  to  the  subject ;  but  once, 
at  least,  it  led  to  marvellous  results.  No  straw  is  so  small 
that  it  may  not  point  the  receptive  mind  of  genius  to 
new  and  wonderful  truths. 

Here,  then,  was  this  obscure  German  physician,  lead- 
ing the  humdrum  life  of  a  village  practitioner,  yet  seeing 
such  visions  as  no  human  being  in  the  world  had  ever 
seen  before. 

The  great  principle  he  had  discovered  became  the 
dominating  thought  of  his  life,  and  filled  all  his  leisure 
hours.  He  applied  it  far  and  wide,  amidst  all  the  phe- 
nomena of  the  inorganic  and  organic  worlds.  It  taught 
him  that  both  vegetables  and  animals  are  machines, 
bound  by  the  same  laws  that  hold  sway  over  inorgan- 
ic matter,  transforming  energy,  but  creating  nothing. 
Then  his  mind  reached  out  into  space  and  met  a  universe 
made  up  of  questions.  Each  star  that  blinked  down  at 
him  as  he  rode  in  answer  to  a  night  call  seemed  an  inter- 
rogation-point asking,  How  do  I  exist?  Why  have  I 
not  long  since  burned  out  if  your  theory  of  conservation 
be  true  ?  No  one  hitherto  had  even  tried  to  answer  that 
question;  few  had  so  much  as  realized  that  it  demanded 
an  answer.  But  the  Heilbronn  physician  understood 
the  question  and  found  an  answer.  His  meteoric  hy- 
pothesis, published  in  1848,  gave  for  the  first  time  a 
tenable  explanation  of  the  persistent  light  and  heat  of 
our  sun  and  the  myriad  other  suns — an  explanation  to 
which  we  shall  recur  in  another  connection. 

All  this  time  our  isolated  philosopher,  his  brain  aflame 
with  the  glow  of  creative  thought,  was  quite  unaware 
that  any  one  else  in  the  world  was  working  along  the 

£16 


THE  CENTURY'S    PROGRESS   IN   PHYSICS 

same  lines.  And  the  outside  world  was  equally  heedless 
of  the  work  of  the  Heilbronn  physician.  There  was  no 
friend  to  inspire  enthusiasm  and  give  courage,  no  kindred 
spirit  to  react  on  this  masterful  but  lonely  mind.  And 
this  is  the  more  remarkable  because  there  are  few  other 
cases  where  a  master -originator  in  science  has  come 
upon  the  scene  except  as  the  pupil  or  friend  of  some 
other  master-originator.  Of  the  men  we  have  noticed 
in  the  present  connection,  Young  was  the  friend  and 
confrere  of  Davy  ;  Davy,  the  protege  of  Kumford  ;  Far- 
raday,  the  pupil  of  Davy ;  Fresnel,  the  co-worker  with 
Arago;  Colding,  the  confrere  of  Oersted;  Joule,  the 
pupil  of  Dalton.  But  Mayer  is  an  isolated  phenomenon 
— one  of  the  lone  mountain-peak  intellects  of  the  century. 
That  estimate  may  be  exaggerated  which  has  called  him 
the  Galileo  of  the  nineteenth  century,  but  surely  no  luke- 
warm praise  can  do  him  justice. 

Yet  for  a  long  time  his  work  attracted  no  attention 
whatever.  In  1847,  when  another  German  physician, 
Hermann  von  Helmholtz,  one  of  the  most  massive  and 
towering  intellects  of  any  age,  had  been  independently 
led  to  comprehension  of  the  doctrine  of  conservation  of 
energy,  and  published  his  treatise  on  the  subject,  he  had 
hardly  heard  of  his  countryman  Mayer.  When  he  did 
hear  .of  him,  however,  he  hastened  to  renounce  all  claim 
to  the  doctrine  of  conservation,  though  the  world  at 
large  gives  him  credit  of  independent  even  though  sub- 
sequent discovery. 

Meantime  in  England  Joule  was  going  on  from  one 
experimental  demonstration  to  another,  oblivious  of  his 
German  competitors  and  almost  as  little  noticed  by  his 
own  countrymen.  He  read  his  first  paper  before  the 
chemical  section  of  the  British  Association  for  the 

217 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

Advancement  of  Science  in  1843,  and  no  one  heeded  it 
in  the  least.  Two  years  later  he  wished  to  read  another 
paper,  but  the  chairman  hinted  that  time  was  limited, 
and  asked  him  to  confine  himself  to  a  brief  verbal  synop- 
sis of  the  results  of  his  experiments.  Had  the  chair- 
man but  known  it,  he  was  curtailing  a  paper  vastly  more 
important  than  all  the  other  papers  of  the  meeting  put 
together.  However,  the  sj'nopsis  was  given,  and  one 
man  was  there  to  hear  it  who  had  the  genius  to  appre- 
ciate its  importance.  This  was  William  Thomson,  the 
present  Lord  Kelvin,  now  known  to  all  the  world  as 
among  the  greatest  of  natural  philosophers,  but  then 
only  a  novitiate  in  science.  He  came  to  Joule's  aid, 
started  rolling  the  ball  of  controversy,  and  subsequently 
associated  himself  with  the  Manchester  experimenter  in 
pursuing  his  investigations. 

But  meantime  the  acknowledged  leaders  of  British 
science  viewed  the  new  doctrine  askance.  Faraday, 
Brewster,  Herschel — those  were  the  great  names  in 
physics  at  that  day,  and  no  one  of  them  could  quite 
accept  the  new  views  regarding  energy.  For  several 
years  no  older  physicist,  speaking  with  recognized 
authority,  came  forward  in  support  of  the  doctrine  of 
conservation.  This  culminating  thought  of  our  first 
half-century  came  silently  into  the  world,  unheralded 
and  unopposed.  The  fifth  decade  of  the  century  had 
seen  it  elaborated  and  substantially  demonstrated  in  at 
least  three  different  countries,  yet  even  the  leaders  of 
thought  did  not  so  much  as  know  of  its  existence.  In 
1853  Whewell,  the  historian  of  the  inductive  sciences,  pub- 
lished a  second  edition  of  his  history,  and,  as  Huxley  has 
pointed  out,  he  did  not  so  much  as  refer  to  the  revolution- 
izing thought  which  even  then  was  a  full  decade  old. 

218 


JAMES  PRESCOTT  JOULE 


WILLIAM  THOMSON    (LORD  KELVIN) 


JULIUS   ROBERT   MAYER 


JOHN  TYNDALL 


THK        ^K 

PWIVERSI2TT 
iftt 


LIB  r< 
'*?•"    0* 


•   i 

THE   CENTURY'S   PROGRESS   IN   PHYSIC 

By  this  time,  however,  the  battle  was  brewing.  The 
rising  generation  saw  the  importance  of  a  law  which 
their  elders  could  not  appreciate,  and  soon  it  was  noised 
abroad  that  there  were  more  than  one  claimant  to  the 
honor  of  discovery.  Chiefly  through  the  efforts  of  Pro- 
fessor Tyndall,  the  work  of  Mayer  became  known  to  the 
British  public,  and  a  most  regrettable  controversy  ensued 
between  the  partisans  of  Mayer  and  those  of  Joule — a 
bitter  controversy,  in  which  Davy's  contention  that 
science  knows  no  country  was  not  always  regarded,  and 
which  left  its  scars  upon  the  hearts  and  minds  of  the 
great  men  whose  personal  interests  were  involved. 

And  so  to  this  day  the  question  who  is  the  chief  dis- 
coverer of  the  law  of  conservation  of  energy  is  not  sus- 
ceptible of  a  categorical  answer  that  would  satisfy  all 
philosophers.  It  is  generally  held  that  the  first  choice 
lies  between  Joule  and  Mayer.  Professor  Tyndall  has 
expressed  the  belief  that  in  future  each  of  these  men 
will  be  equally  remembered  in  connection  with  this 
work.  But  history  gives  us  no  warrant  for  such  a  hope. 
Posterity  in  the  long  run  demands  always  that  its  heroes 
shall  stand  alone.  Who  remembers  now  that  Robert 
Hooke  contested  with  Newton  the  discovery  of  the  doc- 
trine of  universal  gravitation?  The  judgment  of  pos- 
terity is  unjust,  but  it  is  inexorable.  And  so  we  can 
little  doubt  that  a  century  from  now  one  name  will  be 
mentioned  as  that  of  the  originator  of  the  great  doctrine 
of  conservation  of  energy.  The  man  whose  name  is  thus 
remembered  will  perhaps  be  spoken  of  as  the  Galileo, 
the  Newton,  of  the  nineteenth  century;  but  whether 
the  name  thus  dignified  by  the  final  verdict  of  history 
will  be  that  of  Colding,  Mohr,  Mayer,  Helmholtz,  or 
Joule,  it  is  not  for  our  century  to  decide. 

221 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 


IV 

The  gradual  permeation  of  the  field  by  the  great 
doctrine  of  conservation  simply  repeated  the  history 
of  the  introduction  of  every*  novel  and  revolutionary 
thought.  Necessarily  the  elder  generation,  to  whom 
all  forms  of  energy  were  imponderable  fluids,  must  pass 
away  before  the  new  conception  could  claim  the  field. 
Even  the  word  energy,  though  Young  had  introduced 
it  in  1807,  did  not  come  into  general  use  till  some  time 
after  the  middle  of  the  century.  To  the  generality  of 
philosophers  (the  word  physicist  was  even  less  in  favor 
at  this  time)  the  various  forms  of  energy  were  still 
subtle  fluids,  and  never  was  idea  relinquished  with 
greater  unwillingness  than  this.  The  experiments  of 
Young  and  Fresnel  had  convinced  a  large  number  of 
philosophers  that  light  is  a  vibration  and  not  a  sub- 
stance; but  so  great  an  authority  as  Biot  clung  to  the 
old  emission  idea  to  the  end 'of  his  life,  in  1862,  and  held 
a  following. 

Meantime,  however,  the  company  of  brilliant  young 
men  who  had  just  served  their  apprenticeship  when  the 
doctrine  of  conservation  came  upon  the  scene  had  grown 
into  authoritative  positions,  arid  were  battling  actively 
for  the  new  ideas.  Confirmatory  evidence  that  energy 
is  a  molecular  motion  and  not  an  "  imponderable  "  form 
of  matter  accumulated  day  by  day.  The  experiments  of 
two  Frenchmen,  Hippolyte  L.  Fizeau  and  Leon  Foucault, 
served  finally  to  convince  the  last  lingering  sceptics  that 
light  is  an  undulation  ;  and  by  implication  brought  heat 
into  the  same  category,  since  James  David  Forbes,  the 
Scotch  physicist,  had  shown  in  1837  that  radiant  heat 
conforms  to  the  same  laws  of  polarization  and  double 

222 


THE   CENTURY'S   PROGRESS   IN   PHYSICS 

refraction  that  govern  light.  But,  for  that  matter,  the 
experiments  that  had  established  the  mechanical  equiva- 
lent of  heat  hardly  left  room  for  doubt  as  to  the  imma- 
teriality of  this  "imponderable."  Doubters  had,  indeed, 
expressed  scepticism  as  to  the  validity  of  Joule's  exper- 
iments, but  the  further  researches,  experimental  and 
mathematical,  of  such  workers  as  Thomson  (Lord  Kel- 
vin), Rankine,  and  Tyndall  in  Great  Britain,  of  Helra- 
holtz  and  Clausius  in  Germany,  and  of  Regnault  in 
France,  dealing  with  various  manifestations  of  heat, 
placed  the  evidence  beyond  the  reach  of  criticism. 

Out  of  these  studies,  just  at  the  middle  of  the  cen- 
tury, to  which  the  experiments  of  Mayer  and  Joule  had 
led,  grew  the  new  science  of  thermo-dynamics.  Out  of 
them  also  grew  in  the  mind  of  one  of  the  investigators 
a  new  generalization,  only  second  in  importance  to  the 
doctrine  of  conservation  itself.  Professor  William 
Thomson  (Lord  Kelvin)  in  his  studies  in  thermo-dynam- 
ics was  early  impressed  with  the  fact  that  whereas  all 
the  molar  motion  developed  through  labor  or  gravity 
could  be  converted  into  heat,  the  process  is  not  fully  re- 
versible. Heat  can,  indeed,  be  converted  into  molar 
motion  or  work,  but  in  the  process  a  certain  amount  of 
the  heat  is  radiated  into  space  and  lost.  The  same 
tiling  happens  whenever  any  other  form  of  energy  is 
converted  into  molar  motion.  Indeed,  every  transmuta- 
tion of  energy,  of  whatever  character,  seems  compli- 
cated by  a  tendency  to  develop  heat,  part  of  which  is 
lost.  This  observation  led  Professor  Thomson  to  his 
doctrine  of  the  dissipation  of  energy,  which  he  formu- 
lated before  the  Royal  Society  of  Edinburgh  in  1852, 
and  published  also  in  the  Philosophical  Magazine  the 
same  year,  the  title  borne  being,  "  On  a  Universal  Ten- 

223 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

dency  in  Nature  to  the  Dissipation  of  Mechanical  En- 
ergy." 

From  the  principle  here  expressed  Professor  Thomson 
drew  the  startling  conclusion  that,  "  since  any  restora- 
tion of  this  mechanical  energy  without  more  than  an 
equivalent  dissipation  is  impossible,"  the  universe,  as 
known  to  us,  must  be  in  the  condition  of  a  machine 
gradually  running  down  ;  and  in  particular  that  the 
world  we  live  on  has  been  within  a  finite  time  unfit  for 
human  habitation,  and  must  again  become  so  within  a 
finite  future.  This  thought  seems  such  a  commonplace 
to-day  that  it  is  difficult  to  realize  how  startling  it  ap- 
peared half  a  century  ago.  A  generation  trained,  as 
ours  has  been,  in  the  doctrines  of  conservation  and  dis- 
sipation of  energy  as  the  very  alphabet  of  physical  sci- 
ence can  but  ill  appreciate  the  mental  attitude  of  a  gen- 
eration which  for  the  most  part  had  not  even  thought  it 
problematical  whether  the  sun  could  continue  to  give 
out  heat  and  light- forever.  But  those  advance  thinkers 
who  had  grasped  the  import  of  the  doctrine  of  conser- 
vation could  at  once  appreciate  the  force  of  Thomson's 
doctrine  of  dissipation,  and  realize  the  complementary 
character  of  the  two  conceptions. 

Here  and  there  a  thinker  like  Rankine  did,  indeed,  at- 
tempt to  fancy  conditions  under  which  the  energy  lost 
through  dissipation  might  be  restored  to  availability, 
but  no  such  effort  has  met  with  success,  and  in  time 
Professor  Thomson's  generalization  and  his  conclusions 
as  to  the  consequences  of  the  law  involved  came  to  be 
universally  accepted. 

The  introduction  of  the  new  views  regarding  the  nat- 
ure of  energy  followed,  as  I  have  said,  the  course  of 
every  other  growth  of  new  ideas.  Young  and  imagina- 

224 


THE   CENTURY'S   PROGRESS   IN   PHYSICS 

tive  men  could  accept  the  new  point  of  view  ;  older  phi- 
losophers, their  minds  channelled  by  preconceptions, 
could  not  get  into  the  new  groove.  So  strikingly  true 
is  this  in  the  particular  case  now  before  us  that  it  is 
worth  while  to  note  the  ages  at  the  time  of  the  revolu- 
tionary experiments  of  the  men  whose  work  has  been 
mentioned  as  entering  into  the  scheme  of  evolution  of 
the  idea  that  energy  is  merely  a  manifestation  of  matter 
in  motion.  Such  a  list  will  tell  the  story  better  than  a 
volume  of  commentary. 

Observe,  then,  that  Davy  made  his  epochal  experi- 
ment of  melting  ice  by  friction  when  he  was  a  youth  of 
twenty.  Young  was  no  older  when  he  made  his  first 
communication  to  the  Koyal  Society,  and  was  in  his 
twenty -seventh  year  when  he  first  actively  espoused  the 
undulatory  theory.  Fresnel  was  twenty-six  when  he 
made  his  first  important  discoveries  in  the  same  field ; 
and  Arago,  who  at  once  became  his  champion,  was  then 
but  two  years  his  senior,  though  for  a  decade  he  had 
been  so  famous  that  one  involuntarily  thinks  of  him  as 
belonging  to  an  elder  generation. 

Forbes  was  under  thirty  when  he  discovered  the  po- 
larization of  heat,  which  pointed  the  way  to  Mohr,  then 
thirty-one,  to  the  mechanical  equivalent.  Joule  was 
twenty-two  in  1840,  when  his  great  work  was  begun  ; 
and  Mayer,  whose  discoveries  date  from  the  same  year, 
was  then  twenty-six,  which  was  also  the  age  of  Helm- 
holtz  when  he  published  his  independent  discovery  of 
the  same  law.  William  Thomson  was  a  youth  just  past 
his  majority  when  he  came  to  the  aid  of  Joule  before 
the  British  Society,  and  but  seven  jears  older  when  he 
formulated  his  own  doctrine  of  dissipation  of  energy. 
And  Clausius  and  Rankine,  who  are  usually  mentioned 
P  225 


THE  STORY   OF  NINETEENTH-CENTURY   SCIENCE 

with  Thomson  as  the  great  developers  of  thermo-dynam- 
ics,  were  both  far  advanced  with  their  novel  studies 
before  they  were  thirty.  We  may  well  agree  with  the 
father  of  inductive  science  that  "  the  man  who  is  young 
in  years  may  be  old  in  hours." 

Yet  we  must  not  forget  that  the  shield  has  a  reverse 
side.  For  was  not  the  greatest  of  observing  astrono- 
mers, Herschel,  past  thirty-five  before  he  ever  saw  a 
telescope,  and  past  fifty  before  he  discovered  the  heat 
rays  of  the  spectrum?  And  had  not  Faraday  reached 
middle  life  before  he  turned  his  attention  especially  to 
electricity  ?  Clearly,  then,  to  make  his  phrase  complete, 
Bacon  must  have  added  that  "the  man  who  is  old  in 
years  may  be  young  in  imagination."  Here,  however, 
even  more  appropriate  than  in  the  other  case — more's 
the  pity — would  have  been  the  application  of  his  quali- 
fying clause:  "  but  that  happeneth  rarely." 


There  are  only  a  few  great  generalizations  as  yet 
thought  out  in  any  single  field  of  science.  Naturally, 
then,  after  a  great  generalization  has  found  definitive 
expression,  there  is  a  period  of  lull  before  another  for- 
ward move.  In  the  case  of  the  doctrines  of  energy,  the 
lull  has  lasted  half  a  century.  Throughout  this  period, 
it  is  true,  a  multitude  of  workers  have  been  delving  in 
the  field,  and  to  the  casual  observer  it  might  seem  as  if 
their  activity  had  been  boundless,  while  the  practical 
applications  of  their  ideas — as  exemplified,  for  example, 
in  the  telephone,  phonograph,  electric  light,  and  so  on — 
have  been  little  less  than  revolutionary.  Yet  the  most 
competent  of  living  authorities,  Lord  Kelvin,  could  as- 

226 


THE   CENTURY'S   PROGRESS   IN   PHYSICS 

sert  in  1895  that  in  fifty  years  he  had  learned  nothing 
new  regarding  the  nature  of  energy. 

This,  however,  must  not  be  interpreted  as  meaning 
that  the  world  has  stood  still  during  these  two  genera- 
tions. It  means  rather  that  the  rank  and  file  have  been 
moving  forward  along  the  road  the  leaders  had  already 
travelled.  Only  a  few  men  in  the  world  had  the  range 
of  thought  regarding  the  new  doctrine  of  energy  that 
Lord  Kelvin  had  at  the  middle  of  the  century.  The 
few  leaders  then  saw  clearly  enough  that  if  one  form  of 
energy  is  in  reality  merely  an  undulation  or  vibration 
among  the  particles  of  "  ponderable  "  matter  or  of  ether, 
all  other  manifestations  of  energy  must  be  of  the  same 
nature.  But  the  rank  and  file  were  not  even  within 
sight  of  this  truth  for  a  long  time  after  they  had  partly 
grasped  the  meaning  of  the  doctrine  of  conservation. 
When,  late  in  the  fifties,  that  marvellous  young  Scotch- 
man, James  Clerk  Maxwell,  formulating  in  other  words 
an  idea  of  Faraday's,  expressed  his  belief  that  electrici- 
ty and  magnetism  are  but  manifestations  of  various  con- 
ditions of  stress  and  motion  in  the  ethereal  medium 
(electricity  a  displacement  of  strain,  magnetism  a  whirl 
in  the  ether),  the  idea  met  with  no  immediate  populari- 
ty. And  even  less  cordial  was  the  reception  given  the 
same  thinker's  theory,  put  forward  in  1863,  that  the 
ethereal  undulations  producing  the  phenomenon  we  call 
light  differ  in  no  respect  except  in  their  wave-length 
from  the  pulsations  of  electro-magnetism. 

At  about  the  same  time  Helmholtz  formulated  a 
somewhat  similar  electro-magnetic  theory  of  light;  but 
even  the  weight  of  this  combined  authority  could  not 
give  the  doctrine  vogue  until  very  recently,  when  the 
experiments  of  Heinrich  Hertz,  the  pupil  of  Helmholtz, 

227 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

have  shown  that  a  condition  of  electrical  strain  may  be 
developed  into  a  wave  system  by  recurrent  interruptions 
of  the  electric  state  in  the  generator,  and  that  such 
waves  travel  through  the  ether  with  the  rapidity  of 
light.  Since  then  the  electro-magnetic  theory  of  light 
has  been  enthusiastically  referred  to  as  the  greatest  gen- 
eralization of  the  century  ;  but  the  sober  thinker  must 
see  that  it  is  really  only  what  Hertz  himself  called  it- 
one  pier  beneath  the  great  arch  of  conservation.  It  is 
an  interesting  detail  of  the  architecture,  but  the  part 
cannot  equal  the  size  of  the  whole. 

More  than  that,  this  particular  pier  is  as  yet  by  no 
means  a  very  firm  one.  It  has,  indeed,  been  demon- 
strated that  waves  of  electro-magnetism  pass  through 
space  with  the  speed  of  light,  but  as  yet  no  one  has  de- 
veloped electric  waves  even  remotely  approximating  the 
shortness  of  the  visual  rays.  The  most  that  can  posi- 
tively be  asserted,  therefore,  is  that  all  the  known  forms 
of  radiant  energy  —  heat,  light,  electro -magnetism- 
travel  through  space  at  the  same  rate  of  speed,  and  con- 
sist of  traverse  vibrations — "lateral  quivers,"  as  Fresnel 
said  of  light — known  to  differ  in  length,  and  not  posi- 
tively known  to  differ  otherwise.  It  has,  indeed,  been 
suggested  that  the  newest  form  of  radiant  energy,  the 
famous  X  ray  of  Professor  Rontgen's  discovery,  is  a 
longitudinal  vibration,  but  this  is  a  mere  surmise.  Be 
that  as  it  may,  there  is  no  one  now  to  question  that  all 
forms  of  radiant  energy,  whatever  their  exact  affinities, 
consist  essentially  of  undulatory  motions  of  one  uniform 
medium. 

A  full  century  of  experiment,  calculation,  and  con- 
troversy has  thus  sufficed  to  correlate  the  "  impondera- 
ble fluids  "  of  our  forebears,  and  reduce  them  all  to  man- 

228 


THE   CENTURY'S  PROGRESS   IN   PHYSICS 

ifestations  of  motion  among  particles  of  matter.  At 
first  glimpse  that  seems  an  enormous  change  of  view. 
And  yet,  when  closely  considered,  that  change  in 
thought  is  not  so  radical  as  the  change  in  phrase  might 
seem  to  imply.  For  the  nineteenth-century  physicist,  in 
displacing  the  "imponderable  fluids"  of  many  kinds — 
one  each  for  light,  heat,  electricity,  magnetism — has 
been  obliged  to  substitute  for  them  one  all-pervading 
fluid,  whose  various  quivers,  waves,  ripples,  whirls,  or 
strains  produce  the  manifestations  which  in  popular 
parlance  are  termed  forms  of  force.  This  all-pervading 
fluid  the  physicist  terms  the  ether,  and  he  thinks  of  it 
as  having  no  weight.  In  effect,  then,  the  physicist  has 
dispossessed  the  many  imponderables  in  favor  of  a  single 
imponderable — though  the  word  imponderable  has  been 
banished  from  his  vocabulary.  In  this  view  the  ether — 
which, -considered  as  a  recognized  scientific  verity,  is  es- 
sentially a  nineteenth-century  discovery — is  about  the 
most  interesting  thing  in  the  universe.  Something  more 
as  to  its  properties,  real  or  assumed,  we  shall  have  oc- 
casion to  examine  as  we  turn  to  the  obverse  side  of 
physics,  which  demands  our  attention  in  the  next  chap- 
ter. 


CHAPTER  VII 
THE  ETHER  AND  PONDERABLE  MATTER 


"  WHATEVER  difficulties  we  may  have  in  forming  a 
consistent  idea  of  the  constitution  of  the  ether,  there 
can  be  no  doubt  that  the  interplanetary  and  interstellar 
spaces  are  not  empty,  but  are  occupied  by  a  material 
substance  or  body  which  is  certainly  the  largest  and 
probably  the  most  uniform  body  of  which  we  have  any 
knowledge." 

Such  was  the  verdict  pronounced  some  twenty  years 
ago  by  James  Clerk  Maxwell,  one  of  the  very  greatest 
of  nineteenth-century  physicists,  regarding  the  existence 
of  an  all-pervading  plenum  in  the  universe,  in  which 
every  particle  of  tangible  matter  is  immersed.  And  this 
verdict  may  be  said  to  express  the  attitude  of  the  entire 
philosophical  world  of  our  da}^.  Without  exception,  the 
authoritative  physicists  of  our  time  accept  this  plenum 
as  a  verity,  and  reason  about  it  with  something  of  the 
same  confidence  they  manifest  in  speaking  of  "pondera- 
ble "  matter  or  of  energy.  It  is  true  there  are  those  among 
them  who  are  disposed  to  deny  that  this  all-pervading 
plenum  merits  the  name  of  matter.  But  that  it  is  a 
something,  and  a  vastly  important  something  at  that,  all 
are  agreed.  Without  it,  they  allege,  we  should  know 


THE   ETHER  AND   PONDERABLE   MATTER 

nothing  of  light,  of  radiant  heat,  of  electricity,  or  mag- 
netism ;  without  it  there  would  probably  be  no  such 
thing  as  gravitation ;  nay,  they  even  hint  that  without 
this  strange  something,  ether,  there  would  be  no  such 
thing  as  matter  in  the  universe.  If  these  contentions  of 
the  modern  physicist  are  justified,  then  this  intangible 
ether  is  incomparably  the  most  important  as  well  as  the 
"largest  and  most  uniform  substance  or  body"  in  the 
universe.  Its  discovery  may  well  be  looked  upon  as  the 
most  important  feat  of  our  century. 

For  a  discovery  of  our  century  it  surely  is,  in  the 
sense  that  all  the  known  evidences  of  its  existence  have 
been  gathered  in  this  epoch.  True,  dreamers  of  all  ages 
have,  for  metaphysical  reasons,  imagined  the  existence 
of  intangible  fluids  in  space — they  had,  indeed,  peopled 
space  several  times  over  with  different  kinds  of  ethers, 
as  Maxwell  remarks — but  such  vague  dreamings  no  more 
constituted  the  discovery  of  the  modern  ether  than  the 
dream  of  some  pre-Columbian  visionary  that  land  might 
lie  beyond  the  unknown  waters  constituted  the  discov- 
ery of  America.  In  justice  it  must  be  admitted  that 
Huyghens,  the  seventeenth-century  originator  of  the  un- 
dulatory  theory  of  light,  caught  a  glimpse  of  the  true 
ether;  but  his  contemporaries  and  some  eight  genera- 
tions of  his  successors  were  utterly  deaf  to  his  claims ; 
so  he  bears  practically  the  same  relation  to  the  nine- 
teenth-century discoverers  of  ether  that  the  Norseman 
bears  to  Columbus. 

The  true  Columbus  of  the  ether  was  Thomas  Young. 
His  discovery  was  consummated  in  the  early  days  of  the 
present  century,  when  he  brought  forward  the  first  con- 
clusive proofs  of  the  undulato^  theory  of  light.  To 
say  that  light  consists  of  undulations  is  to  postulate 

231 


THE   STORY   OF   NINETEENTH-CENTURY  SCIENCE 

something  which  undulates ;  and  this  something  could 
not  be  air,  for  air  exists  only  in  infinitesimal  quantity,  if 
at  all,  in  the  interstellar  spaces,  through  which  light 
freely  penetrates.  But  if  not  air,  what  then?  Why, 
clearly,  something  more  intangible  than  air;  something 
supersensible,  evading  all  direct  efforts  to  detect  it,  yet 
existing  everywhere  in  seemingly  vacant  space,  and  also 
interpenetrating  the  substance  of  all  transparent  liquids 
and  solids,  if  not,  indeed,  of  all  tangible  substances. 
This  intangible  something  Young  rechristened  the  Lu- 
miniferous  Ether. 

In  the  early  days  of  his  discovery  Young  thought  of 
the  undulations  which  produce  light  and  radiant  heat  as 
being  longitudinal — a  forward  and  backward  pulsation, 
corresponding  to  the  pulsations  of  sound — and  as  such 
pulsations  can  be  transmitted  by  a  fluid  medium  with 
the  properties  of  ordinary  fluids,  he  was  justified  in 
thinking  of  the  ether  as  being  like  a  fluid  in  its  proper- 
ties, except  for  its  extreme  intangibility.  But  about 
1818  the  experiments  of  Fresnel  and  Arago  with  polar- 
ization of  light  made  it  seem  very  doubtful  whether  the 
theory  of  longitudinal  vibrations  is  sufficient,  and  it  was 
suggested  by  Young,  and  independently  conceived  and 
demonstrated  by  Fresnel,  that  the  luminiferous  undula- 
tions are  not  longitudinal,  but  transverse;  and  all  the 
more  recent  experiments  have  tended  to  confirm  this 
view.  But  it  happens  that  ordinary  fluids — gases  and 
liquids — cannot  transmit  lateral  vibrations;  only  rigid 
bodies  are  capable  of  such  a  vibration.  So  it  became 
necessary  to  assume  that  the  luminiferous  ether  is  a  body 
possessing  elastic  rigidity — a  familiar  property  of  tangi- 
ble solids,  but  one  quite  unknown  among  fluids. 

The  idea  of  transverse  vibrations  carried  with  it  an- 

232 


THE   ETHER   AND   PONDERABLE   MATTER 

other  puzzle.  Why  does  not  the  ether,  when  set  aquiver 
with  the  vibration  which  gives  us  the  sensation  we  call 
light,  have  produced  in  its  substance  subordinate  quiv- 
ers, setting  out  at  right  angles  from  the  path  of  the 
original  quiver?  Such  perpendicular  vibrations  seem 
not  to  exist,  else  we  might  see  around  a  corner;  how 
explain  their  absence?  The  physicists  could  think  of 
but  one  way :  they  must  assume  that  the  ether  is  in- 
compressible. It  must  fill  all  space — at  any  rate,  all 
space  with  which  human  knowledge  deals — perfectly 
full. 

These  properties  of  the  ether,  incompressibility  and 
elastic  rigidity,  are  quite  conceivable  by  themselves; 
but  difficulties  of  thought  appear  when  we  reflect  upon 
another  quality  which  the  ether  clearly  must  possess — 
namely,  frictionlessness.  Per  hypothesis  this  rigid,  in- 
compressible body  pervades  all  space,  imbedding  every 
particle  of  tangible  matter;  yet  it  seems  not  to  retard  the 
movements  of  this  matter  in  the  slightest  degree.  This 
is  undoubtedly  the  most  difficult  to  comprehend  of  the 
alleged  properties  of  the  ether.  The  physicist  explains 
it  as  due  to  the  perfect  elasticity  of  the  ether,  in  virtue 
of  which  it  closes  in  behind  a  moving  particle  with  a 
push  exactly  counterbalancing  the  stress  required  to 
penetrate  it  in  front. 

To  a  person  unaccustomed  to  think  of  seemingly 
solid  matter  as  really  composed  of  particles  relatively 
wide  apart,  it  is  hard  to  understand  the  claim  that 
ether  penetrates  the  substance  of  solids — of  glass,  for 
example — and,  to  use  Young's  expression,  which  we 
have  previously  quoted,  moves  among  them  as  freely 
as  the  wind  moves  through  a  grove  of  trees.  This 
thought,  however,  presents  few  difficulties  to  the  mind 

233 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

accustomed  to  philosophical  speculation.  But  the  ques- 
tion early  arose  in  the  mind  of  Fresnel  whether  the 
ether  is  not  considerably  affected  by  contact  with  the 
particles  of  solids.  Some  of  his  experiments  led  him  to 
believe  that  a  portion  of  the  ether  which  penetrates 
among  the  molecules  of  tangible  matter  is  held  captive, 
so  to  speak,  and  made  to  move  along  with  these  par- 
ticles. He  spoke  of  such  portions  of  the  ether  as 
"  bound  "  ether,  in  contradistinction  to  the  great  mass 
of  "free"  ether.  Half  a  century  after  Fresnel's  death, 
when  the  ether  hypothesis  had  become  an  accepted  len- 
et  of  science,  experiments  were  undertaken  by  Fizeau 
in  France,  and  by  Maxwell  in  England,  to  ascertain 
whether  any  portion  of  ether  is  really  thus  bound  to 
particles  of  matter ;  but  the  results  of  the  experiments 
were  negative,  and  the  question  is  still  undetermined. 

While  the  undulatory  theory  of  light  was  still  fighting 
its  way,  another  kind  of  evidence  favoring  the  existence 
of  an  ether  was  put  forward  by  Michael  Faraday,  who, 
in  the  course  of  his  experiments  in  electrical  and  mag- 
netic induction,  was  led  more  and  more  to  perceive  def- 
inite lines  or  channels  of  force  in  the  medium  subject  to 
electro-magnetic  influence.  Faraday's  mind,  like  that 
of  Newton  and  many  other  philosophers,  rejected  the 
idea  of  action  at  a  distance,  and  he  felt  convinced  that 
the  phenomena  of  magnetism  and  of  electric  induction 
told  strongly  for  the  existence  of  an  invisible  plenum 
everywhere  in  space,  which  might  very  probably  be 
the  same  plenum  that  carried  the  undulations  of  light 
and  radiant  heat. 

Then,  about  the  middle  of  the  century,  came  that  final 
revolution  of  thought  regarding  the  nature  of  energy 
which  we  have  already  outlined  in  the  preceding  chap- 

234 


THE   ETHER  AND   PONDERABLE   MATTER 

ter,  and  with  that  the  case  for  ether  was  considered  to 
be  fully  established.  The  idea  that  energy  is  merely  a 
"  mode  of  motion  "  (to  adopt  TyndalPs  familiar  phrase), 
combined  with  the  universal  rejection  of  the  notion  of 
action  at  a  distance,  made  the  acceptance  of  a  plenum 
throughout  space  a  necessity  of  thought — so,  at  any 
rate,  it  has  seemed  to  most  physicists  of  recent  decades. 
The  proof  that  all  known  forms  of  radiant  energy  move 
through  space  at  the  same  rate  of  speed  is  regarded  as 
practically  a  demonstration  that  but  one  plenum — one 
ether — is  concerned  in  their  transmission.  It  has,  in- 
deed, been  tentatively  suggested,  by  Professor  J.  Oliver 
Lodge,  that  there  may  be  two  ethers,  representing  the 
two  opposite  kinds  of  electricity,  but  even  the  author 
of  this  hypothesis  would  hardly  claim  for  it  a  high  de- 
gree of  probability. 

The  most  recent  speculations  regarding  the  properties 
of  the  ether  have  departed  but  little  from  the  early  ideas 
of  Young  and  Fresnel.  It  is  assumed  on  all  sides  that 
the  ether  is  a  continuous,  incompressible  body,  possess- 
ing rigidity  and  elasticity.  Lord  Kelvin  has  even  cal- 
culated the  probable  density  of  this  ether,  and  its  coeffi- 
cient of  rigidity.  As  might  be  supposed,  it  is  all  but 
infinitely  tenuous  as  compared  with  any  tangible  solid, 
and  its  rigidity  is  but  infinitesimal  as  compared  with 
that  of  steel.  In  a  word,  it  combines  properties  of 
tangible  matter  in  a  way  not  known  in  any  tangible 
substance.  Therefore  we  cannot  possibly  conceive  its 
true  condition  correctly.  The  nearest  approximation, 
according  to  Lord  Kelvin,  is  furnished  by  a  mould  of 
transparent  jelly.  It  is  a  crude,  inaccurate  analogy,  of 
course,  the  density  and  resistance  of  jelly  in  particular 
being  utterly  different  from  those  of  the  ether ;  but  the 

235 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

quivers  that  run  through  the  jelly  when  it  is  shaken, 
and  the  elastic  tension  under  which  it  is  placed  when  its 
mass  is  twisted  about,  furnish  some  analogy  to  the  quiv- 
ers and  strains  in  the  ether,  which  are  held  to  constitute 
radiant  energy,  magnetism,  and  electricity. 

The  great  physicists  of  the  day  being  at  one  regarding 
the  existence- of  this  all-pervading  ether,  it  would  be  a 
manifest  presumption  for  any  one  standing  without  the 
pale  to  challenge  so  firmly  rooted  a  belief.  And,  in- 
deed, in  any  event,  there  seems  little  ground  on  which 
to  base  such  a  challenge.  Yet  it  may  not  be  altogether 
amiss  to  reflect  that  the  physicist  of  to-day  is  no  more 
certain  of  his  ether  than  was  his  predecessor  of  the 
eighteenth  century  of  the  existence  of  certain  alleged 
substances  which  he  called  phlogiston,  caloric,  corpuscles 
of  light,  and  magnetic  and  electric  fluids.  It  would  be 
but  the  repetition  of  history  should  it  chance  that  be- 
fore the  close  of  another  century  the  ether  should  have 
taken  its  place  along  with  these  discarded  creations  of 
the  scientific  imagination  of  earlier  generations.  The 
philosopher  of  to-day  feels  very  sure  that  an  ether  ex- 
ists ;  but  when  he  says  there  is  "  no  doubt "  of  its  exist- 
ence he  speaks  incautiously,  and  steps  beyond  the  bounds 
of  demonstration.  He  does  not  know  that  action  cannot 
take  place  at  a  distance ;  he  does  not  know  that  empty 
space  itself  may  not  perform  the  functions  which  he 
ascribes  to  his  space-filling  ether. 


ii 

Meantime,  however^  the  ether,  be  it  substance  or  be 
it  only  dream-stuff,  is  serving  an  admirable  purpose  in 
furnishing  a  fulcrum  for  modern  physics.  Not  alone 


THE  ETHER  AND   PONDERABLE   MATTER 

to  the  student  of  energy  has  it  proved  invaluable,  but  to 
the  student  of  matter  itself  as  well.     Out  of  its  hypo- 


HETCMANN   LTTDWTO   FERDINAND   TTELMHOLT7 

From  a  photograph  by  Loescher  and  Petsch,  Berlin 


THE   STORY    OF   NINETEENTH-CENTURY   SCIENCE 

thetical  mistiness  has  been  reared  the  most  tenable 
theory  of  the  constitution  of  ponderable  matter  which 
has  yet  been  suggested— or,  at  any  rate,  the  one  that 
will  stand  as  the  definitive  nineteenth-century  guess  at 
this-"  riddle  of  the  ages."  I  mean,  of  course,  the  vortex 
theory  of  atoms — that  profound  and  fascinating  doctrine 
which  suggests  that  matter,  in  all  its  multiform  phases, 
is  nothing  more  or  less  than  ether  in  motion. 

The  author  of  this  wonderful  conception  is  Lord  Kel- 
vin. The  idea  was  born  in  his  mind  of  a  happy  union 
of  mathematical  calculations  with  concrete  experiments. 
The  mathematical  calculations  were  largely  the  work  of 
Hermann  von  Helmholtz,  who,  about  the  year  1858,  had 
undertaken  to  solve  some  unique  problems  in  vortex 
motions.  Helmholtz  found  that  a  vortex  whirl,  once  es- 
tablished in  a  frictionless  medium,  must  go  on,  theoret- 
ically, unchanged  forever.  In  a  limited  medium  such  a 
whirl  may  be  Y-shaped,  with  its  ends  at  the  surface  of 
the  medium.  We  may  imitate  such  a  vortex  by  drawing 
the  bowl  of  a  spoon  quickly  through  a  cup  of  water. 
But  in  a  limitless  medium  the  vortex  whirl  must  always 
be  a  closed  ring,  which  may  take  the  simple  form  of  a 
hoop  or  circle,  or  which  may  be  indefinitely  contorted, 
looped,  or,  so  to  speak,  knotted.  Whether  simple  or 
contorted,  this  endless  chain  of  whirling  matter  (the 
particles  revolving  about  the  axis  of  the  loop  as  the  par- 
ticles of  a  string  revolve  when  the  string  is  rolled  be- 
tween the  fingers)  must,  in  a  frictionless  medium,  retain 
its  form,  and  whirl  on  with  undiminished  speed  forever. 

While  these  theoretical  calculations  of  Helmholtz  were 
fresh  in  his  mind,  Lord  Kelvin  (then  Sir  William  Thom- 
son) was  shown  by  Professor  P.  G.  Tait,  of  Edinburgh, 
an  apparatus  constructed  for  the  purpose  of  creating 


THE   ETHER   AND   PONDERABLE   MATTER 

vortex  rings  in  air.  The  apparatus,  which  any  one  may 
duplicate,  consisted  simply  of  a  box  with  a  hole  bored 
in  one  side,  and  a  piece  of  canvas  stretched  across  the 
opposite  side  in  lieu  of  boards.  Fumes  of  chloride  of 
ammonia  are  generated  within  the  box,  merely  to  render 
the  air  visible.  By  tapping  with  the  hand  on  the  canvas 
side  of  the  box,  vortex  rings  of  the  clouded  air  are  driven 
out,  precisely  similar  in  appearance  to  those  smoke-rings 
which  some  expert  tobacco-smokers  can  produce  by  tap- 
ping on  their  cheeks,  or  to  those  larger  ones  which  we 
sometimes  see  blown  out  from  the  funnel  of  a  locomo- 
tive. 

The  advantage  of  Professor  Tait's  apparatus  is  its 
manageableness,  and  the  certainty  with  which  the  de- 
sired result  can  be  produced.  Before  Lord  Kelvin's  in- 
terested observation  it  threw  out  rings  of  various  sizes, 
which  moved  straight  across  the  room  at  varying  rates 
of  speed,  according  to  the  initial  impulse,  and  which  be- 
haved very  strangely  when  coming  in  contact  with  one 
another.  If,  for  example,  a  rapidly  moving  ring  over- 
took another  moving  in  the  same  path,  the  one  in  ad- 
vance seemed  to  pause,  and  to  spread  out  its  periphery 
like  an  elastic  band,  while  the  pursuer  seemed  'to  con- 
tract, till  it  actually  slid  through  the  orifice  of  the  other, 
after  which  each  ring  resumed  its  original  size,  and  con- 
tinued its  course  as  if  nothing  had  happened.  When,  on 
the  other  hand,  two  rings  moving  in  slightly  different  di- 
rections came  near  each  other,  they  seemed  to  have  an 
attraction  for  each  other ;  yet  if  they  impinged,  they 
bounded  away,  quivering  like  elastic  solids.  If  an  effort 
were  made  to  grasp  or  to  cut  one  of  these  rings,  the  subtle 
thing  shrunk  from  the  contact,  and  slipped  away  as  if  it 
were  alive. 


THE   STORY   OF   NINETEENTH-CENTURY  SCIENCE 

And  all  the  while  the  body  which  thus  conducted 
itself  consisted  simply  of  a  whirl  in  the  air,  made  visi- 
ble, but  not  otherwise  influenced,  by  smoky  fumes. 
Presently  the  friction  of  the  surrounding  air  wore  the 
ring  away,  and  it  faded  into  the  general  atmosphere— 
often,  however,  not  until  it  had  persisted  for  many  sec- 
onds, and  passed  clear  across  a  large  room.  Clearly,  if 
there  were  no  friction,  the  ring's  inertia  must  make  it  a 
permanent  structure.  Only  the  frictionless  medium  was 
lacking  to  fulfil  all  the  conditions  of  Helmholtz's  inde- 
structible vortices.  And  at  once  Lord  Kelvin  bethought 
him  of  the  frictionless  medium  which  physicists  had  now 
begun  to  accept— the  all-pervading  ether.  What  if  vor- 
tex rings  were  started  in  this  ether,  must  they  not  have 
the  properties  which  the  vortex  rings  in  air  had  exhib- 
ited— inertia,  attraction,  elasticity  ?  And  are  not  these 
the  properties  of  ordinary  tangible  matter?  Is  it  not 
probable,  then,  that  what  we  call  matter  consists  merely 
of  aggregations  of  infinitesimal  vortex  rings  in  the 
ether? 

Thus  the  vortex  theory  of  atoms  took  form  in  Lord 
Kelvin's  mind,  and  its  expression  gave  the  world  what 
many  philosophers  of  our  time  regard  as  the  plausible 
conception  of  the  constitution  of  matter  hitherto  formu- 
lated. It  is  only  a  theory,  to  be  sure ;  its  author  would 
be  the  last  person  to  claim  finality  for  it.  "It  is  only  a 
dream,"  Lord  Kelvin  said  to  me,  in  referring  to  it  not  long 
ago.  But  it  has  a  basis  in  mathematical  calculation  and 
in  analogical  experiment  such  as  no  other  theory  of  mat- 
ter can  lay  claim  to,  and  it  has  a  unifying  or  monistic 
tendency  that  makes  it,  for  the  philosophical  mind,  little 
less  than  fascinating.  True  or  false,  it  is  the  definitive 
theory  of  matter  of  the  nineteenth  century. 

240 


THE  ETHER  AND   PONDERABLE   MATTER 


in 

Quite  aside  from  the  question  of  the  exact  constitu- 
tion of  the  ultimate  particles  of  matter,  questions  as  to 
the  distribution  of  such  particles,  their  mutual  relations, 
properties,  and  actions,  have  come  in  for  a  full  share  of 
attention  during  our  century,  though  the  foundations 
for  the  modern  speculations  were  furnished  in  a  pre- 
vious epoch.  The  most  popular  eighteenth -century 
speculation  as  to  the  ultimate  constitution  of  matter 
was  that  of  the  learned  Italian  priest,  Eoger  Joseph 
Boscovich,  published  in  1758,  in  his  Theoria  Philoso- 
phic® Naturalis.  "  In  this  theory,"  according  to  an 
early  commentator,  "  the  whole  mass  of  which  the 
bodies  of  the  universe  are  composed  is  supposed  to  con- 
sist of  an  exceedingly  great  yet  finite  number  of  simple, 
indivisible,  inextended  atoms.  These  atoms  are  endued 
by  the  Creator  with  repulsive  and  attractive  forces, 
which  vary  according  to  the  distance.  At  very  small 
distances  the  particles  of  matter  repel  each  other ;  and 
this  repulsive  force  increases  beyond  all  limits  as  the 
distances  are  diminished,  and  will  consequently  forever 
prevent  actual  contact.  When  the  particles  of  matter 
are  removed  to  sensible  distances,  the  repulsive  is  ex- 
changed for  an  attractive  force,  which  decreases  in  in- 
verse ratio  with  the  squares  of  the  distances,  and  extends 
beyond  the  spheres  of  the  most  remote  comets." 

This  conception  of  the  atom  as  a  mere  centre  of  force 
was  hardly  such  as  could  satisfy  any  mind  other  than 
the  metaphysical.  No  one  made  a  conspicuous  attempt 
to  improve  upon  the  idea,  however,  till  just  at  the  close 
of  the  century,  when  Humphry  Davy  was  led,  in  the 
course  of  his  studies  of  heat,  to  speculate  as  to  the 
Q  241 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

changes  that  occur  in  the  intimate  substance  of  matter 
under  altered  conditions  of  temperature.  Davy,  as  we 
have  seen,  regarded  heat  as  a  manifestation  of  motion 
among  the  particles  of  matter.  As  all  bodies  with 
which  we  come  in  contact  have  some  temperature,  Davy 
inferred  that  the  intimate  particles  of  every  substance 
must  be  perpetually  in  a  state  of  vibration.  Such  vibra- 
tions, he  believed,  produced  the  "repulsive  force"  which 
(in  common  with  Boscovich)  he  admitted  as  holding  the 
particles  of  matter  at  a  distance  from  one  another.  To 
heat  a  substance  means  merely  to  increase  the  rate  of 
vibration  of  its  particles ;  thus  also,  plainly,  increasing 
the  repulsive  forces,  and  expanding  the  bulk  of  the  mass 
as  a  whole.  If  the  degree  of  heat  applied  be  sufficient, 
the  repulsive  force  may  become  strong  enough  quite  to 
overcome  the  attractive  force,  and  the  particles  will  sep- 
arate and  tend  to  fly  away  from  one  another,  the  solid 
then  becoming  a  gas. 

Not  much  attention  was  paid  to  these  very  suggestive 
ideas  of  Davy,  because  they  were  founded  on  the  idea 
that  heat  is  merely  a  motion,  which  the  scientific  world 
then  repudiated  ;  but  half  a  century  later,  when  the  new 
theories  of  energy  had  made  their  way,  there  came  a 
revival  of  practically  the  same  ideas  of  the  particles  of 
matter  (molecules  they  were  now  called)  which  Davy 
had  advocated.  Then  it  was  that  Clausius  in  Germany 
and  Clerk  Maxwell  in  England  took  up  the  investigation 
of  what  came  to  be  known  as  the  kinetic  theory  of  gases 
—the  now  familiar  conception  that  all  the  phenomena 
of  gases  are  due  to  the  helter-skelter  flight  of  the  show- 
ers of  widely  separated  molecules  of  which  they  are 
composed.  The  specific  idea  that  the  pressure  or 
"spring"  of  gases  is  due  to  such  molecular  impacts  was 

243 


THE  ETHER  AND  PONDERABLE  MATTER 

due  to  Daniel  Bournelli,  who  advanced  it  early  in  the 
eighteenth  century.  The  idea,  then  little  noticed,  had 
been  revived  about  a  century  later  by  William  Hera- 
path,  and  again  with  some  success  by  J.  J.  Waterston, 
of  Bombay,  about  1846;  but  it  gained  no  distinct  foot- 
ing until  taken  in  hand  by  Clausius  in  1857  and  by 
Maxwell  in  1859. 

The  investigations  of  these  great  physicists  not  only 
served  fully  to  substantiate  the  doctrine,  but  threw  a 
flood  of  light  upon  the  entire  subject  of  molecular  dy- 
namics. Soon  the  physicists  came  to  feel  as  certain  of 
the  existence  of  these  showers  of  flying  molecules  mak- 
ing up  a  gas  as  if  they  could  actually  see  and  watch 
their  individual  actions.  Through  study  of  the  viscosity 
of  gases — that  is  to  say,  of  the  degree  of  frictional  oppo- 
sition they  show  to  an  object  moving  through  them  or 
to  another  current  of  gas — an  idea  was  gained,  with  the 
aid  of  mathematics,  of  the  rate  of  speed  at  which  the 
particles  of  the  gas  are  moving,  and  the  number  of  col- 
lisions which  each  particle  must  experience  in  a  given 
time,  and  of  the  length  of  the  average  free  path  trav- 
ersed by  the  molecule  between  collisions.  These  meas- 
urements were  confirmed  by  study  of  the  rate  of  diffusion 
at  which  different  gases  mix  together,  and  also  by  the 
rate  of  diffusion  of  heat  through  a  gas,  both  these  phe- 
nomena being  chiefly  due  to  the  helter-skelter  flight  of 
the  molecules. 

It  is  sufficiently  astonishing  to  be  told  that  such 
measurements  as  these  have  been  made  at  all,  but  the 
astonishment  grows  when  one  hears  the  results.  It  ap- 
pears from  Maxwell's  calculations  that  the  mean  free 
path,  or  distance  traversed  by  the  molecules  between 
collisions  in  ordinary  air,  is  about  one  half-millionth  of 

243 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

an  inch  ;  while  the  speed  of  the  molecules  is  such  that 
each  one  experiences  about  eight  billions  of  collisions 
per  second  !  It  would  be  hard,  perhaps,  to  cite  an  illus- 
tration showing  the  refinements  of  modern  physics  bet- 
ter than  this;  unless,  indeed,  one  other  result  that  fol- 
lowed directly  from  these  calculations  be  considered 
such  —  the  feat,  namely,  of  measuring  the  size  of  the 
molecules  themselves.  Clausius  was  the  first  to  point 
out  how  this  might  be  done  from  a  knowledge  of  the 
length  of  free  path ;  and  the  calculations  were  made  by 
Loschmidt  in  Germany,  and  by  Lord  Kelvin  in  England, 
independently. 

The  work  is  purely  mathematical,  of  course,  but  the 
results  are  regarded  as  unassailable ;  indeed,  Lord  Kelvin 
speaks  of  them  as  being  absolutely  demonstrative  within 
certain  limits  of  accuracy.  This  does  not  mean,  how- 
ever, that  they  show  the  exact  dimensions  of  the  mole- 
cule ;  it  means  an  estimate  of  the  limits  of  size  within 
which  the  actual  size  of  the  molecule  may  lie.  These 
limits,  Lord  Kelvin  estimates,  are  about  the  one  ten- 
millionth  of  a  centimetre  for  the  maximum,  and  the  one 
one-hundred-millionth  of  a  centimetre  for  the  minimum. 
Such  figures  convey  no  particular  meaning  to  our  blunt 
senses,  but  Lord  Kelvin  has  given  a  tangible  illustration 
that  aids  the  imagination  to  at  least  a  vague  comprehen- 
sion of  the  unthinkable  smallness  of  the  molecule.  He 
estimates  that  if  a  ball,  say  of  water  or  glass,  about  "  as 
large  as  a  football,  were  to  be  magnified  up  to  the  size 
of  the  earth,  each  constituent  molecule  being  magnified 
in  the  same  proportion,  the  magnified  structure  would 
be  more  coarse-grained  than  a  heap  of  shot,  but  proba- 
bly less  coarse-grained  than  a  heap  of  footballs." 

Several  other  methods  have  been  employed,  to  estimate 

244 


THE   ETiiER   AND   PONDERABLE   MATTER 

the  size  of  molecules.  One  of  these  is  based  upon  the 
phenomena  of  contact  electricity  ;  another  upon  the 
wave-theory  of  light;  and  another  upon  capillary  at- 
traction, as  shown  in  the  tense  film  of  a  soap-bubble! 
No  one  of  these  methods  gives  results  more  definite  than 
that  due  to -the  kinetic  theory  of  gases,  just  outlined; 
but  the  important  thing  is  that  the  results  obtained  by 
these  different  methods  (all  of  them  due  to  Lord  Kelvin) 
agree  with  one  another  in  fixing  the  dimensions  of  the 
molecule  at  somewhere  about  the  limits  already  men- 
tioned. We  may  feel  very  sure  indeed,  therefore,  that 
the  ultimate  particles  of  matter  are  not  the  unextended, 
formless  points  which  Boscovich  and  his  followers  of  the 
last  century  thought  them. 


IV 

Whatever  the  exact  form  of  the  molecule,  its  outline  is 
subject  to  incessant  variation  ;  for  nothing  in  molecular 
science  is  regarded  as  more  firmly  established  than  that 
the  molecule,  under  all  ordinary  circumstances,  is  in  a 
state  of  intense  but  variable  vibration.  The  entire  en- 
ergy of  a  molecule  of  gas,  for  example,  is  not  measured 
by  its  momentum,  but  by  this  plus  its  energy  of  vibra- 
tion and  rotation,  due  to  the  collisions  already  referred 
to.  Clausius  has  even  estimated  the  relative  importance 
of  these  two  quantities,  showing  that  the  translational 
motion  of  a  molecule  of  gas  accounts  for  only  three- 
fifths  of  its  kinetic  energy.  The  total  energy  of  the 
molecule  (which  we  call  "  heat ")  includes  also  another 
factor,  namely,  potential  energy,  or  energy  of  position, 
due  to  the  work  that  has  been  done  on  expanding,  in 
overcoming  external  pressure,  and  internal  attraction 

245 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

between  the  molecules  themselves.  This  potential  en- 
ergy (which  will  be  recovered  when  the  gas  contracts)  is 
the  "  latent  heat "  of  Black,  which  so  long  puzzled  the 
philosophers.  It  is  latent  in  the  same  sense  that  the  en- 
ergy of  a  ball  thrown  into  the  air  is  latent  at  the  mo- 
ment when  the  ball  poises  at  its  greatest  height  before 
beginning  to  fall. 

It  thus  appears  that  a  variety  of  motions,  real  and  po- 
tential, enter  into  the  production  of  the  condition  we 
term  heat.  It  is,  however,  chiefly  the  translational  mo- 
tion which  is  measurable  as  temperature ;  and  this,  too, 
which  most  obviously  determines  the  physical  state  of 
the  substance  that  the  molecules  collectively  compose— 
whether,  that  is  to  say,  it  shall  appear  to  our  blunt  per- 
ceptions as  a  gas,  a  liquid,  or  a  solid.  In  the  gaseous 
state,  as  we  have  seen,  the  translational  motion  of  the 
molecules  is  relatively  enormous,  the  molecules  being 
widely  separated.  It  does  not  follow,  as  we  formerly 
supposed,  that  this  is  evidence  of  a  repulsive  power  act- 
ing between  the  molecules.  The  physicists  of  to-day, 
headed  by  Lord  Kelvin,  decline  to  recognize  any  such 
power.  They  hold  that  the  molecules  of  a  gas  fly  in 
straight  lines  in  virtue  of  their  inertia,  quite  indepen- 
dently of  one  another,  except  at  times  of  collision,  from 
which  they  rebound  in  virtue  of  their  elasticity ;  or  an 
approach  to  collision,  in  which  latter  case,  coming  with- 
in the  range  of  mutual  attraction,  two  molecules  may 
circle  about  one  another,  as  a  comet  circles  about  the 
sun,  theii  rush  apart  again,  as  the  comet  rushes  from 
the  sun. 

It  is  obvious  that  the  length  of  the  mean  free  path  of 
the  molecules  of  a  gas  may  be  increased  indefinitely  by 
decreasing  the  number  of  the  molecules  thernselves  in  a 

246 


THE   ETHER   AND   PONDERABLE   MATTER 

circumscribed  space.  It  has  been  shown  by  Professors 
Tait  and  Dewar  that  a  vacuum  may  be  produced  arti- 
ficially of  such  a  degree  of  rarefaction  that  the  mean 
free  path  of  the  remaining  molecules  is  measurable  in 
inches.  The  calculation  is  based  on  experiments  made 
with  the  radiometer  of  Professor  Crookes,  an  instru- 
ment which  in  itself  is  held  to  demonstrate  the  truth  of 
the  kinetic  theory  of  gases.  Such  an  attenuated  gas  as 
this  is  considered  by  Professor  Crookes  as  constituting  a 
fourth  state  of  matter,  which  he  terms  ultra-gaseous. 

If,  on  the  other  hand,  a  gas  is  subjected  to  pressure, 
its  molecules  are  crowded  closer  together,  and  the  length 
of  their  mean  free  path  is  thus  lessened.  Ultimately,  the 
pressure  being  sufficient,  the  molecules  are  practically 
in  continuous  contact.  Meantime  the  enormously  in- 
creased number  of  collisions  has  set  the  molecules  more 
and  more  actively  vibrating,  and  the  temperature  of  the 
gas  has  increased,  as,  indeed,  necessarily  results  in  ac- 
cordance with  the  law  of  the  conservation  of  energy. 
No  amount  of  pressure,  therefore,  can  suffice  by  itself  to 
reduce  the  gas  to  a  liquid  state.  It  is  believed  that 
even  at  the  centre  of  the  sun,  where  the  pressure  is  al- 
most inconceivably  great,  all  matter  is  to  be  regarded  as 
really  gaseous,  though  the  molecules  must  be  so  packed 
together  that  the  consistency  is  probably  more  like  that 
of  a  solid. 

If,  however,  coincidently  with  the  application  of  press- 
ure, opportunity  be  given  for  the  excess  of  heat  to  be 
dissipated  to  a  colder  surrounding  medium,  the  mole- 
cules, giving  off  their  excess  of  energy,  become  relative- 
ly quiescent,  and  at  a  certain  stage  the  gas  becomes  a 
liquid.  The  exact  point  at  which  this  transformation 
occurs,  however,  differs  enormously  for  different  sub- 

347 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

stances.  In  the  case  of  water,  for  example,  it  is  a  tem- 
perature more  than  four  hundred  degrees  above  zero, 
Centigrade;  while  for  atmospheric  air  it  is  194°  Centi- 
grade below  zero,  or  more  than  a  hundred  and  fifty  de- 
grees below  the  point  at  which  mercury  freezes. 

Be  it  high  or  low,  the  temperature  above  which  any 
substance  is  always  a  gas,  regardless  of  pressure,  is 
called  the  critical  temperature,  or  absolute  boiling-point, 
of  that  substance.  It  does  not  follow,  however,  that 
below  this  point  the  substance  is  necessarily  a  liquid. 
This  is  a  matter  that  will  be  determined  by  external 
conditions  of  pressure.  Even  far  below  the  critical  tem- 
perature the  molecules  have  an  enormous  degree  of  ac- 
tivity, and  tend  to  fly  asunder,  maintaining  what  ap- 
pears to  be  a  gaseous,  but  what  technically  is  called  a 
vaporous,  condition — the  distinction  being  that  pressure 
alone  suffices  to  reduce  the  vapor  to  the  liquid  state. 
Thus  water  may  change  from  the  gaseous  to  the  liquid 
state  at  four  hundred  degrees  above  zero,  but  under 
conditions  of  ordinary  atmospheric  pressure  it  does  not 
do  so  until  the  temperature  is  lowered  three  hundred 
degrees  further.  Below  four  hundred  degrees,  however, 
it  is  technically  a  vapor,  not  a  gas ;  but  the  sole  diifer- 
ence,  it  will  be  understood,  is  in  the  degree  of  molecular 
activity. 

It  thus  appears  that  the  prevalence  of  water  in  a 
vaporous  and  liquid  rather  than  in  a  "permanently" 
gaseous  condition  here  on  the  globe  is  a  mere  incident 
of  telluric  evolution.  Equally  incidental  is  the  fact  that 
the  air  we  breathe  is  "  permanently  "  gaseous  and  not 
liquid  or  solid,  as  it  might  be  were  the  earth's  surface 
temperature  to  be  lowered  to  a  degree  which,  in  the 
larger  view,  may  be  regarded  as  trifling.  Between  the 

348 


TI1E   ETHER   AND   PONDERABLE   MATTER 

atmospheric  temperature  in  tropical  and  in  arctic  regions 
there  is  often  a  variation  of  more  than  one  hundred  de- 
grees; were  the  temperature  reduced  another  hundred, 
the  point  would  be  reached  at  which  oxygen  gas  becomes 
a  vapor,  and  under  increased  pressure  would  be  a  liquid. 
Thirty-seven  degrees  more  would  bring  us  to  the  critical 
temperature  of  nitrogen. 

Nor  is  this  a  mere  theoretical  assumption ;  it  is  a 
determination  of  experimental  science,  quite  indepen- 
dent of  theory.  The  physicist  in  the  laboratory  has 
produced  artificial  conditions  of  temperature  enabling 
him  to  change  the  state  of  the  most  persistent  gases. 
Some  fifty  years  since,  when  the  kinetic  theory  was  in 
its  infancy,  Faraday  liquefied  carbonic  acid  gas,  among 
others,  and  the  experiments  thus  inaugurated  have  been 
extended  by  numerous  more  recent  investigators,  notably 
by  Cailletet  in  Switzerland,  by  Pictet  in  France,  and  by 
Dr.  Thomas  Andrews  and  Professor  James  Dewar  in 
England.  In  the  course  of  these  experiments  not  only 
has  air  been  liquefied,  but  hydrogen  also,  the  most  subtle 
of  gases ;  and  it  has  been  made  more  and  more  apparent 
that  gas  and  liquid  are,  as  Andrews  long  ago  asserted, 
"  only  distant  stages  of  a  long  series  of  continuous  phys- 
ical changes."  Of  course  if  the  temperature  be  lowered 
still  further,  the  liquid  becomes  a  solid  ;  and  this  change 
also  has  been  effected  in  the  case  of  some  of  the  most 
"  permanent "  gases,  including  air. 

The  degree  of  cold — that  is,  of  absence  of  heat — thus 
produced  is  enormous,  relatively  to  anything  of  which 
we  have  experience  in  nature  here  at  the  earth  now, 
yet  the  molecules  of  solidified  air,  for  example,  are  not 
absolutely  quiescent.  In  other  words,  they  still  have  a 
temperature,  though  so  very  low.  But  it  is  clearly  con- 

349 


THE   STORY  OF   NINETEENTH-CENTURY   SCIENCE 

ceivable  that  a  stage  might  be  reached  at  which  the 
molecules  became  absolutely  quiescent,  as  regards  either 
translational  or  vibratory  motion.  Such  a  heatless  con- 
dition has  been  approached,  but  as  yet  not  quite  attained, 
in  laboratory  experiments.  It  is  called  the  absolute 
zero  of  temperature,  and  is  estimated  to  be  equivalent 
to  273°  Centigrade  below  the  freezing-point  of  water,  or 
ordinary  zero. 

A  temperature  (or  absence  of  temperature)  closely 
approximating  this  is  believed  to  obtain  in  the  ethereal 
ocean  of  interplanetary  and  interstellar  space,  which 
transmits,  but  is  thought  not  to  absorb,  radiant  energy. 
We  here  on  the  earth's  surface  are  protected  from  ex- 
posure to  this  cold,  which  would  deprive  every  organic 
thing  of  life  almost  instantaneously,  solely  by  the  thin 
blanket  of  atmosphere  with  which  the  globe  is  coated. 
It  would  seem  as  if  this  atmosphere,  exposed  to  such  a 
temperature  at  its  surface,  must  there  be  incessantly 
liquefied,  and  thus  fall  back  like  rain  to  be  dissolved 
into  gas  again  while  it  still  is  many  miles  above  the 
earth's  surface.  This  may  be  the  reason  why  its  scurry- 
ing molecules  have  not  long  ago  wandered  off  into  space, 
and  left  the  world  without  protection. 

But  whether  or  not  such  liquefaction  of  the  air  now 
occurs  in  our  outer  atmosphere,  there  can  be  no  question 
as  to  what  must  occur  in  its  entire  depth  were  we  per- 
manently shut  off  from  the  heating  influence  of  the  sun, 
as  the  astronomers  threaten  that  we  may  be  in  a  future 
age.  Each  molecule,  not  alone  of  the  atmosphere,  but  of 
the  entire  earth's  substance,  is  kept  aquiver  by  the  energy 
which  it  receives,  or  has  received,  directly  or  indirectly, 
from  the  sun.  Left  to  itself,  each  molecule  would  wear 
out  its  energy  and  fritter  it  off  into  the  space  about  it, 

250 


THE   ETHER   AND   PONDERABLE   MATTER 

ultimately  running  completely  down,  as  surely  as  any 
human-made  machine  whose  power  is  not  from  time  to 
time  restored.  If  then  it  shall  come  to  pass  in  some 
future  age  that  the  sun's  rays  fail  us,  the  temperature 
of  the  globe  must  gradually  sink  towards  the  absolute 
zero.  That  is  to  say,  the  molecules  of  gas  which  now 
fly  about  at  such  inconceivable  speed  must  drop  helpless 
to  the  earth ;  liquids  must  in  turn  become  solids ;  and 
solids  themselves,  their  molecular  quivers  utterly  stilled, 
may  perhaps  take  on  properties  the  nature  of  which  we 
cannot  surmise. 

Yet  even  then,  according  to  the  current  hypothesis, 
the  heatless  molecule  will  still  be  a  thing  instinct  with 
life.  Its  vortex  whirl  will  still  go  on,  uninfluenced  by 
the  dying  out  of  those  subordinate  quivers  that  produced 
the  transitory  effect  which  we  call  temperature.  For 
those  transitory  thrills,  though  determining  the  physical 
state  of  matter  as  measured  by  our  crude  organs  of  sense, 
were  no  more  than  non-essential  incidents;  but  the  vortex 
whirl  is  the  essence  of  matter  itself. 


CHAPTER  VIII 
THE  CENTURY'S  PROGRESS  IN  CHEMISTRY 


SMALL  beginnings  have  great  endings — sometimes. 
As  a  case  in  point,  note  what  came  of  the  small  original 
effort  of  a  self-trained  back-country  Quaker  youth  named 
John  Dal  ton,  who  along  towards  the  close  of  the  last 
century  became  interested  in  the  weather,  and  was  led 
to  construct  and  use  a  crude  rain-gauge  to  test  the 
amount  of  the  waterfall.  The  simple  experiments  thus 
inaugurated  led  to  no  fewer  than  two  hundred  thousand 
recorded  observations  regarding  the  weather,  which 
formed  the  basis  for  some  of  the  most  epochal  discov- 
eries in  meteorology,  as  we  have  seen.  But  this  was 
only  a  beginning.  The  simple  rain-gauge  pointed  the 
way.to  the  most  important  generalization  of  our  century 
in  a  field  of  science  with  which,  to  the  casual  observer, 
it  might  seem  to  have  no  alliance  whatever.  The  won- 
derful theory  of  atoms,  on  which  the  whole  gigantic 
structure  of  modern  chemistry  is  founded,  was  the  logical 
outgrowth,  in  the  mind  of  John  Dalton,  of  those  early 
studies  in  meteorology. 

The  way  it  happened  was  this :  From  studying  the 
rainfall,  Dalton  turned  naturally  to  the  complementary 
process  of  evaporation.  He  was  soon  led  to  believe  that 

253 


I  UNIVER' 


SIN, 


THE   CENTURY'S   PROGRESS 

vapor  exists  in  the  atmosphere  as  an  independent  gas. 
But  since  two  bodies  cannot  occupy  the  same  space  at 
the  same  time,  this  implies  that  the  various  atmospheric 
gases  are  really  composed  of  discrete  particles.  These 
ultimate  particles  are  so  small  that  we  cannot  see  them 
— cannot,  indeed,  more  than  vaguely  imagine  them— 
yet  each  particle  of  vapor,  for  example,  is  just  as  much 
a  portion  of  water  as  if  it  were  a  drop  out  of  the  ocean, 
or,  for  that  matter,  the  ocean  itself.  But  again,  water 
is  a  compound  substance,  for  it  may  be  separated,  as 
Cavendish  had  shown,  into  the  two  elementary  sub- 
stances hydrogen  and  oxygen.  Hence  the  atom  of 
water  must  be  composed  of  two  lesser  atoms  joined 
together.  Imagine  an  atom  of  hydrogen  and  one  of 
oxygen.  Unite  them,  and  we  have  an  atom  of  water ; 
sever  them,  and  the  water  no  longer  exists ;  but  whether 
united  or  separate  the  atoms  of  hydrogen  and  of  oxygen 
remain  hydrogen  and  oxygen  and  nothing  else.  Differ- 
ently mixed  together  or  united,  atoms  produce  different 
gross  substances;  but  the  elementary  atoms  never  change 
their  chemical  nature — their  distinct  personality. 

It  was  about  the  year  1803  that  Dalton  first  gained  a 
full  grasp  of  the  conception  of  the  chemical  atom.  At 
once  he  saw  that  the  hypothesis,  if  true,  furnished  a 
marvellous  key  to  secrets  of  matter  hitherto  insoluble- 
questions  relating  to  the  relative  proportions  of  the 
atoms  themselves.  It  is  known,  for  example,  that  a 
certain  bulk  of  Irvdrogen  gas  unites  with  a  certain  bulk 
of  oxygen  gas  to  form  water.  If  it  be  true  that  this 
combination  consists  essentially  of  the  union  of  atoms 
one  with  another  (each  single  atom  of  hydrogen  united 
to  a  single  atom  of  oxygen),  then  the  relative  weights 
of  the  original  masses  of  hydrogen  and  of  oxygen  must 

203 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

be  also  the  relative  weights  of  each  of  their  respective 
atoms.  If  one  pound  of  hydrogen  unites  with  five  and 
one-half  pounds  of  oxygen  (as,  according  to  Dalton's 
experiments,  it  did),  then  the  weight  of  the  oxygen 


JOHN   D ALTON 

atom  must  be  five  and  one-half  times  that  of  the  hydro- 
gen atom.  Other  compounds  may  plainly  be  tested  in 
the  same  way.  Dalton  made  numerous  tests  before  he 
published  his  theory.  He  found  that  hydrogen  enters 
into  compounds  in  smaller  proportions  than  any  other 
element  known  to  him,  and  so,  for  convenience,  deter- 
mined to  take  the  weight  of  the  hydrogen  atom  as  unity. 

254 


THE   CENTURY'S   PROGRESS   IN   CHEMISTRY 

The  atomic  weight  of  oxygen  then  becomes  (as  given  in 
Dalton's  first  table  of  1803)  5.5 ;  that  of  water  (hydrogen 
plus  oxygen)  being  of  course  6.5.  The  atomic  .weights 
of  about  a  score  of  substances  are  given  in  Dalton's  first 
paper,  which  was  read  before  the  Literary  and  Philo- 
sophical Society  of  Manchester,  October  21,  1803.  1 
wonder  if  Dalton  himself,  great  and  acute  intellect 
though  he  had,  suspected,  when  he  read  that  paper,  that 
he  was  inaugurating  one  of  the  most  fertile  movements 
ever  entered  on  in  the  whole  history  of  science  \ 


IT 

Be  that  as  it  may,  it  is  certain  enough  that  Dalton's 
contemporaries  were  at  first  little  impressed  with  the 
novel  atomic  theory.  Just  at  this  time,  as  it  chanced,  a 
dispute  was  waging  in  the  field  of  chemistry  regarding 
a  matter  of  empirical  fact  which  must  necessarily  be 
settled  before  such  a  theory  as  that  of  Dalton  could 
even  hope  for  a  hearing.  This  was  the  question  whether 
or  not  chemical  elements  unite  with  one  another  always 
in  definite  proportions.  Berthollet,  the  great  co-worker 
with  La\Toisier,  and  now  the  most  authoritative  of  living 
chemists,  contended  that  substances  combine  in  almost 
indefinitely  graded  proportions  between  fixed  extremes. 
He  held  that  solution  is  really  a  form  of  chemical  com- 
bination— a  position  which,  if  accepted,  left  no  room  for 
argument. 

But  this  contention  of  the  master  was  most  actively 
disputed,  in  particular  by  Louis  Joseph  Proust,  and  al) 
chemists  of  repute  were  obliged  to  take  sides  with  one 
or  the  other.  For  a  time  the  authority  of  Berthollet 
held  out  against  the  facts,  but  at  last  accumulated  evi- 

255 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

dence  told  for  Proust  and  his  followers,  and  towards  the 
close  of  the  first  decade  of  our  century  it  came  to  be 
generally  conceded  that  chemical  elements  combine  with 
one  another  in  fixed  and  definite  proportions. 

More  .than  that.  As  the  analysts  were  led  to  weigh 
carefully  the  quantities  of  combining  elements,  it  was 
observed  that  the  proportions  are  not  only  definite,  but 
that  they  bear  a  very  curious  relation  to  one  another. 
If  element  A  combines  with  two  different  proportions  of 
element  B  to  form  two  compounds,  it  appeared  that  the 
weight  of  the  larger  quantity  of  B  is  an  exact  multiple 
of  that  of  the  smaller  quantity.  This  curious  relation 
was  noticed  by  Dr.  Wollaston,  one  of  the  most  accurate 
of  observers,  and  a  little  later  it  was  confirmed  by  Johan 
Jakob  Berzelius,  the  great  Swedish  chemist,  who  was  to 
be  a  dominating  influence  in  the  chemical  world  for  a 
generation  to  come.  But  this  combination  of  elements 
in  numerical  proportions  was  exactly  what  Dalton  had 
noticed  as  early  as  1802,  and  what  had  led  him  directly 
to  the  atomic  weights.  So  the  confirmation  of  this 
essential  point  by  chemists  of  such  authority  gave  the 
strongest  confirmation  to  the  atomic  theory. 

During  these  same  years  the  rising  authority  of  the 
French  chemical  world,  Joseph  Louis  Gay-Lussac,  was 
conducting  experiments  with  gases,  which  he  had  un- 
dertaken at  first  in  conjunction  with  Humboldt,  but 
which  later  on  were  conducted  independently.  In  1809, 
the  next  year  after  the  publication  of  the  first  volume 
of  Dalton's  New  System  of  Chemical  Philosophy,  Gay- 
Lussac  published  the  results  of  his  observations,  and 
among  other  things  brought  out  the  remarkable  fact 
that  gases,  under  the  same  conditions  as  to  temperature 
and  pressure,  combine  always  in  definite  numerical 

356 


THE   CENTURY'S   PROGRESS   IN-  CHEMISTRY 

proportions  as  to  volume.  Exactly  two  volumes  of 
hydrogen,  for  example,  combine  with  one  volume  of 
oxygen  to  form  water.  Moreover,  the  resulting  com- 
pound gas  always  bears  a  simple  relation  to  the  com- 
bining volumes.  In  the  case  just  cited  the  union  of  two 


JOSEPH    LOUIS    GAY-LUSSAC 


volumes  of  hydrogen  and  one  of  oxygen  results  in  pre- 
cisely two  volumes  of  water  vapor. 

Naturally  enough  the  champions  of  the  atomic  theory 
seized  upon  these  observations  of  Gay-Lussac  as  lending 
strong  support  to  their  hypothesis — all  of  them,  that  is, 
but  the  curiously  self-reliant  and  self-sufficient  author  of 
the  atomic  theory  himself,  who  declined  to  accept  the 
B  257 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

observations  of  the  French  chemist  as  valid.  Yet  the 
observations  of  Gay-Lussac  were  correct,  as  countless 
chemists  since  then  have  demonstrated  anew,  and  his 
theory  of  combination  by  volumes  became  one  of  the 
foundation-stones  of  the  atomic  theory,  despite  the  op- 
position of  the  author  of  that  theory. 

The  true  explanation  of  Gay-Lussac's  law  of  combina- 
tion by  v.olumes  was  thought  out  almost  immediately  by 
an  Italian  savant,  Amadeo  Avogadro,  and  expressed  in 
terms  of  the  atomic  theory.  The  fact  must  be,  said 
Avogadro,  that  under  similar  physical  conditions  every 
form  of  gas  contains  exactly  the  same  number  of  ulti- 
mate particles  in  a  given  volume.  Each  of  these  ulti- 
mate physical  particles  may  be  composed  of  two  or  more 
atoms  (as  in  the  case  of  water  vapor),  but  such  a  com- 
pound atom  conducts  itself  as  if  it  were  a  simple  and 
indivisible  atom,  as  regards  the  amount  of  space  that  sep- 
arates it  from  its  fellows  under  given  conditions  of  press- 
ure and  temperature.  The  compound  atom,  composed 
of  two  or  more  elementary  atoms,  Avogadro  proposed 
to  distinguish,  for  purposes  of  convenience,  by  the  name 
molecule.  It  is  to  the  molecule,  considered  as  the 
unit  of  physical  structure,  that  Avogadro's  law  applies. 

This  vastly  important  distinction  between  atoms  and 
molecules,  implied  in  the  law  just  expressed,  was  pub- 
lished in  1811.  Four  years  later,  the  famous  French 
physicist  Ampere  outlined  a  similar  theoiy,  and  utilized 
the  law  in  his  mathematical  calculations.  And  with  that 
the  law  of  Avogadro  dropped  out  of  sight  for  a  full  gen- 
eration. Little  suspecting  that  it  was  the  very  key  to 
the  inner  mysteries  of  the  atoms  for  which  they  were 
seeking,  the  chemists  of  the  time  cast  it  aside,  and  let 
it  fade  from  the  memory  of  their  science. 

258 


THE   CENTURY'S   PROGRESS   IN  CHEMISTRY 

This,  however,  was  not  strange,  for  of  course  the  law 
of  Avogadro  is  based  on  the  atomic  theory,  and  in  1811 
the  atomic  theory  was  itself  still  being  weighed  in  the 
balance.  The  law  of  multiple  proportions  found  general 
acceptance  as  an  empirical  fact ;  but  many  of  the  leading 
lights  of  chemistry  still  looked  askance  at  Dalton's  ex- 
planation of  this  law.  Thus  Wollaston,  though  from 
the  first  he  inclined  to  acceptance  of  the  Daltonian  view, 
cautiously  suggested  that  it  would  be  well  to  use  the 
non-committal  word  "equivalent"  instead  of  "atom"; 
and  Davy,  for  a  similar  reason,  in  his  book  of  1812, 
speaks  only  of  "  proportions,"  binding  himself  to  no 
theory  as  to  what  might  be  the  nature  of  these  propor- 
tions. 

At  least  two  great  chemists  of  the  time,  however,  adopt- 
ed the  atomic  view  with  less  reservation.  One  of  these 
was  Thomas  Thomson,  professor  at  Edinburgh,  who  in 
1807  had  given  an  outline  of  Dalton's  theory  in  a  widely 
circulated  book,  which  first  brought  the  theory  to  the 
general  attention  of  the  chemical  world.  The  other, 
and  even  more  noted  advocate  of  the  atomic  theory, 
was  Johan  Jakob  Berzelius.  This  great  Swedish  chem- 
ist at  once  set  to  work  to  put  the  atomic  theory  to  such 
tests  as  might  be  applied  in  the  laboratory.  He  was  an 
analyst  of  the  utmost  skill,  ami  for  years  he  devoted 
himself  to  the  determination  of  the  combining  weights, 
"equivalents,"  or  "proportions"  of  the  different  ele- 
ments. These  determinations,  in  so  far  as  they  were 
accurately  made,  were  simple  expressions  of  empirical 
facts,  independent  of  any  theory  ;  but  gradually  it  be- 
came more  and  more  plain  that  these  facts  all  har- 
monize with  the  atomic  theory  of  Dalton.  So  by  com- 
mon consent  the  proportionate  combining  weights  of 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

the  elements  came  to  be  known  as  atomic  weights — 
the  name  Dalton  had  given  them  from  the  first — and 
the  tangible  conception  of  the  chemical  atom  as  a  body 
of  definite  constitution  and  weight  gained  steadily  in 
favor. 

From  the  outset  the  idea  had  had  the  utmost  tangibil- 
ity in  the  mind  of  Dalton.  He  had  all  along  represented 
the  different  atoms  by  geometrical  symbols — as  a  circle 
for  oxygen,  a  circle  enclosing  a  dot  for  hydrogen,  and 
the  like — and  had  represented  "compounds  by  placing 
these  symbols  of  the  elements  in  juxtaposition.  Berzelius 
proposed  to  improve  upon  this  method  by  substituting 
for  the  geometrical  symbol  the  initial  of  the  Latin  name 
of  the  element  represented — O  for  oxygen,  H  for  hy- 
drogen, and  so  on  —  a  numerical  coefficient  to  follow 
the  letter  as  an  indication  of  the  number  of  atoms  pres- 
ent in  any  given  compound.  This  simple  system  soon 
gained  general  acceptance,  and  with  slight  modifica- 
tions it  is  still  universally  employed.  Every  school- 
boy now  is  aware  that  H2O  is  the  chemical  way  of  ex- 
pressing the  union  of  two  atoms  of  hydrogen  with  one 
of  oxygen  to  form  a  molecule  of  water.  But  such  a 
formula  would  have  had  no  meaning  for  the  wisest 
chemist  before  the  day  of  Berzelius. 

The  universal  fame  of  the  great  Swedish  authority 
served  to  give  general  currency  to  his  symbols  and 
atomic  weights,  and  the  new  point  of  view  thus  devel- 
oped led  presently  to  two  important  discoveries  which 
removed  the  last  lingering  doubts  as  to  the  validity 
of  the  atomic  theory.  In  1819  two  French  physicists, 
Dulong  and  Petit,  while  experimenting  with  heat,  dis- 
covered that  the  specific  heats  of  solids  (that  is  to  say, 
the  amount  of  heat  required  to  raise  the  temperature  of 


THE   CENTURY'S    PROGRESS   IN   CHEMISTRY 

a  given  mass  to  a  given  degree)  vary  inversely  as  their 
atomic  weights.  In  the  same  yearEilhard  Mitscherlich, 
a  German  investigator,  observed  that  compounds  having 
the  same  number  of  atoms  to  the  molecule  are  disposed 
to  form  the  same  angles  of  crystallization — a  property 
which  he  called  isomorphism. 


JOHAN   JAKOB   BEKZELIUS 

Here,  then,  were  two  utterly  novel  and  independent 
sets  of  empirical  facts  which  harmonize  strangely  with 
the  supposition  that  substances  are  composed  of  chemical 
atoms  of  a  determinate  weight.  This  surely  could  not 
be  coincidence — it  tells  of  law.  And  so  as  soon  as  the 
claims  of  Dulong  and  Petit  and  of  Mitscherlich  had 
been  substantiated  by  other  observers,  the  laws  of  the 

261 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

specific  heat  of  atoms,  and  of  isomorphism,  took  their 
place  as  new  levers  of  chemical  science.  With  the  aid 
of  these  new  tools  an  impregnable  breastwork  of  facts 
was  soon  piled  about  the  atomic  theory.  And  John 
Dalton,  the  author  of  that  theory,  plain,  provincial 
Quaker,  working  on  to  the  end  in  semi-retirement,  be- 
came known  to  all  the  world  and  for  all  time  as  a  mas- 
ter of  masters. 

in 

During  those  early  years  of  our  century,  when  Dalton 
was  grinding  away  at  chemical  fact  and  theory  in  his 
obscure  Manchester  laboratory,  another  Englishman  held 
the  attention  of  the  chemical  world  with  a  series  of  the 
most  brilliant  and  widely  heralded  researches.  Hum- 
phry Davy  had  come  to  London  in  1801,  at  the  instance 
of  Count  Rumford,  to  assume  the  chair  of  chemical  phi- 
losophy in  the  Eoyal  Institution,  which  the  famous 
American  had  just  founded. 

Here,  under  Davy's  direction,  the  largest  voltaic  bat- 
tery yet  constructed  had  been  put  in  operation,  and  with 
its  aid  the  brilliant  young  experimenter  was  expected  al- 
most to  perform  miracles.  And  indeed  he  scarcely  disap- 
pointed the  expectation,  for  with  the  aid  of  his  battery 
he  transformed  so  familiar  a  substance  as  common  pot- 
ash into  a  metal  which  was  not  only  so  light  that  it 
floated  on  water,  but  possessed  the  seemingly  mirac- 
ulous property  of  bursting  into  flames  as  soon  as  it 
came  in  contact  with  that  fire-quenching  liquid.  If 
this  were  not  a  miracle,  it  had  for  the  popular  eye  all 
the  appearance  of  the  miraculous. 

What  Davy  really  had  done  was  to  decompose  the 
potash,  which  hitherto  had  been  supposed  to  be  elemen- 

'202 


THE   CENTURY'S   PROGRESS   IN   CHEMISTRY 

tary,  liberating  its  0x3- gen,  and  thus  isolating  its  metallic 
base,  which  he  named  potassium.  The  same  thing  was 
done  with  soda,  and  the  closely  similar  metal  sodium 
was  discovered — metals  of  a  unique  type,  possessed  of  a 
strange  avidity  for  oxygen,  and  capable  of  seizing  on  it 
even  when  it  is  bound  up  in  the  molecules  of  water. 
Considered  as  mere  curiosities,  these  discoveries  were  in- 
teresting, but  aside  from  that  they  were  of  great  theo- 
retical importance,  because  they  showed  the  compound 
nature  of  some  familiar  chemicals  that  had  been  re- 
garded as  elements.  Several  other  elementary  earths 
met  the  same  fate  when  subjected  to  the  electrical  in- 
fluence, the  metals  barium,  calcium,  and  strontium  being 
thus  discovered.  Thereafter  Davy  always  referred  to 
the  supposed  elementary  substances  (including  oxygen, 
hydrogen,  and  the  rest)  as  "  undecompounded"  bodies. 
These  resist  all  present  efforts  to  decompose  them,  but 
how  can  one  know  what  might  not  happen  were  they 
subjected  to  an  influence,  perhaps  some  day  to  be  dis- 
covered, which  exceeds  the  battery  in  power  as  the  bat- 
tery exceeds  the  blow-pipe? 

Another  and  even  more  important  theoretical  result 
that  flowed  from  Davy's  experiments  during  this  first 
decade  of  the  century  was  the  proof  that  no  elementary 
substances  other  than  hydrogen  and  oxygen  are  produced 
when  pure  water  is  decomposed  by  the  electric  current. 
It  was  early  noticed  by  Davy  and  others  that  when  a 
strong  current  is  passed  through  water,  alkalies  appear 
at  one  pole  of  the  battery  and  acids  at  the  other,  and 
this  though  the  water  used  were  absolutely  pure.  This 
seemingly  told  of  the  creation  of  elements — a  transmuta- 
tion but  one  step  removed  from  the  creation  of  matter 
itself — under  the  influence  of  the  new  "force."  It  was 

263' 


THE   STORY  OF   NINETEENTH-CENTURY   SCIENCE 

one  of  Davy's  greatest  triumphs  to  prove,  in  the  series 
of  experiments  recorded  in  his  famous  Bakerian  lecture 
of  1806,  that  the  alleged  creation  of  elements  did  not 
take  place,  the  substances  found  at  the  poles  of  the  bat- 
tery having  been  dissolved  from  the  walls  of  the  vessels 
in  which  the  water  experimented  upon  had  been  placed. 
Thus  the  same  implement  which  had  served  to  give  a 
certain  philosophical  warrant  to  the  fading  dreams  of 
alchemy  banished  those  dreams  peremptorily  from  the 
domain  of  present  science. 

Though  the  presence  of  the  alkalies  and  acids  in  the 
water  was  explained,  however,  their  respective  migra- 
tions to  the  negative  and  positive  poles  of  the  battery 
remained  to  be  accounted  for.  Davy's  classical  expla- 
nation assumed  that  different  elements  differ  among 
themselves  as  to  their  electrical  properties,  some  being 
positively,  others  negatively,  electrified.  Electricity 
and  "chemical  affinity,"  he  said,  apparently  are  mani- 
festations of  the  same  force,  acting  in  the  one  case  on 
masses,  in  the  other  on  particles.  Electro-positive  par- 
ticles unite  with  electro-negative  particles  to  form  chem- 
ical compounds,  in  virtue  of  the  familiar  principle  that 
opposite  electricities  attract  one  another.  When  com- 
pounds are  decomposed  by  the  battery,  this  mutual  at- 
traction is  overcome  by  the  stronger  attraction  of  the 
poles  of  the  battery  itself. 

This  theory  of  binary  composition  of  all  chemical 
compounds,  through  the  union  of  electro-positive  and 
electro-negative  atoms  or  molecules,  was  extended  by 
Berzelius,  and  made  the  basis  of  his  famous  system  of 
theoretical  chemistry.  This  theory  held  that  all  inor- 
ganic compounds,  however  complex  their  composition, 
are  essentially  composed  of  such  binary  combinations. 

264 


THE  CENTURY'S   PROGRESS   IN   CHEMISTRY 

For  many  years  this  view  enjoyed  almost  undisputed 
sway.  It  received  what  seemed  strong  contirmation 
when  Faraday  showed  the  definite  connection  between 
the  amount  of  electricity  employed  and  the  amount  of 
decomposition  produced  in  the  so-called  electrolyte. 
But  its  claims  were  really  much  too  comprehensive,  as 
subsequent  discoveries  proved. 


IV 


"When  Berzelius  first  promulgated  his  binary  theory 
he  was  careful  to  restrict  its  unmodified  application  to 
the  compounds  of  the  inorganic  world.  At  that  time, 
and  for  a  long  time  thereafter,  it  was  supposed  that  sub- 
stances of  organic  nature  had  some  properties  that  kept 
them  aloof  from  the  domain  of  inorganic  chemistry.  It 
was  little  doubted  that  a  so-called  "  vital  force  "  oper- 
ated here,  replacing  or  modifying  the  action  of  ordinary 
"chemical  affinity."  It  was,  indeed,  admitted  that  or- 
ganic compounds  are  composed  of  familiar  elements— 
chiefly  carbon,  oxygen,  hydrogen,  and  nitrogen— but 
these  elements  were  supposed  to  be  united  in  ways  that 
could  not  be  imitated  in  the  domain  of  the  non-living. 
It  was  regarded  almost  as  an  axiom  of  chemistry  that 
no  organic  compound  whatever  could  be  put  together 
from  its  elements — synthesized — in  the  laboratory.  To 
effect  the  synthesis  of  even  the  simplest  organic  com- 
pound it  was  thought  that  the  "  vital  force"  must  be  in 
operation. 

Therefore  a  veritable  sensation  was  created  in  the 
chemical  world  when,  in  the  year  1828,  it  was  an- 
nounced that  the  young  German  chemist  Fried  rich 
Wohler,  formerly  pupil  of  Berzelius,  and  already  known 

265 


THE   STORY   OF   NINETEENTH -CENTURY   SCIENCE 

as  a  coining  master,  had  actually  synthesized  the  well- 
known  organic  product  urea  in  his  laboratory  at  Sacrow. 
The  "exception  which  proves  the  rule"  is  something 
never  heard  of  iii  the  domain  of  logical  science.  Nat- 
ural law  knows  no  exceptions.  80  the  synthesis  of  a 
single  organic  compound  sufficed  at  a  blow  to  break 
down  the  chemical  barrier  which  the  imagination  of  the 
fathers  of  the  science  had  erected  between  animate  and 
inanimate  nature.  Thenceforth  the  philosophical  chem- 
ist would  regard  the  plant  and  animal  organisms  as 
chemical  laboratories  in  which  conditions  are  peculiarly 
favorable  for  building  up  complex  compounds  of  a  few 
familiar  elements,  under  the  operation  of  universal 
chemical  laws.  The  chimera  "  vital  force "  could  no 
longer  gain  recognition  in  the  domain  of  chemistry. 

Now  a  wave  of  interest  in  organic  chemistry  swept 
over  the  chemical  world,  and  soon  the  study  of  carbon 
compounds  became  as  much  the  fashion  as  electro-chem- 
istry had  been  in  the  preceding  generation. 

Foremost  among  the  workers  who  rendered  this  epoch 
of  organic  chemistry  memorable  were  Justus  Liebig  in 
Germany  and  Jean  Baptiste  Andre  Dumas  in  France, 
and  their  respective  pupils,  Charles  Frederic  Gerhardt 
and  Augustus  Laurent.  Wdhler,  too,  must  be  named  in 
the  same  breath,  as  also  must  Louis  Pasteur,  who, 
though  somewhat  younger  than  the  others,  came  upon 
the  scene  in  time  to  take  chief  part  in  the  most  impor- 
tant of  the  controversies  that  grew  out  of  their  labors. 

Several  years  earlier  than  this  the  way  had  been 
paved  for  the  study  of  organic  substances  by  Gay-Lus- 
sac's  discovery,  made  in  1815,  that  a  certain  compound 
of  carbon  and  nitrogen,  which  he  named  cyanogen,  has 
a  peculiar  degree  of  stability  which  enables  it  to  retain 

266 


THE   CENTURY'S   PROGRESS   IN   CHEMISTRY 

its  identity,  and  enter  into  chemical  relations  after  the 
manner  of  a  simple  body.  A  year  later  Ampere  discov- 
ered that  nitrogen  and  hydrogen,  when  combined  in  cer- 
tain proportions  to  form  what  he  called  ammonium, 


- 


JUSTUS   VON    LIEBIG 


have  the  same  property.  Berzelius  had  seized  upon  this 
discovery  of  the  compound  radical,  as  it  was  called,  be- 
cause it  seemed  to  lend  aid  to  his  dualistic  theory.  He 
conceived  the  idea  that  all  organic  compounds  are  bi- 
nary unions  of  various  compound  radicals  with  an  atom 
of  oxygen,  announcing  this  theory  in  1818.  Ten  years 

267 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

later,  Liebig  and  Wohler  undertook  a  joint  investigation 
which  resulted  in  proving  that  compound  radicals  are 
indeed  very  abundant  among  organic  substances.  Thus 
the  theory  of  Berzelius  seemed  to  be  substantiated,  and 
organic  chemistry  came  to  be  defined  as  the  chemistry 
of  compound  radicals. 

But  even  in  the  day  of  its  seeming  triumph  the  dual- 
istic  theory  was  destined  to  receive  a  rude  shock.  This 
came  about  through  the  investigations  of  Dumas,  who 
proved  that  in  a  certain  organic  substance  an  atom  of 
hydrogen  may  be  removed,  and  an  atom  of  chlorine 
substituted  in  its  place  without  destroying  the  integrity 
of  the  original  compound — much  as  a  child  might  sub- 
stitute one  block  for  another  in  its  play-house.  Such  a 
substitution  would  be  quite  consistent  with  the  dualistic 
theory,  were  it  not  for  the  very  essential  fact  that  hy- 
drogen is  a  powerfully  electro-positive  element,  while 
chlorine  is  as  strongly  electro-negative.  Hence  the 
compound  radical  which  united  successively  with  these 
two  elements  must  itself  be  at  one  time  electro-positive, 
at  another  electro-negative — a  seeming  inconsistency 
which  threw  the  entire  Berzelian  theory  into  disfavor. 

In  its  place  there  was  elaborated,  chiefly  through  the 
efforts  of  Laurent  and  Gerhardt,  a  conception  of  the 
molecule  as  a  unitary  structure,  built  up  through  the 
aggregation  of  various  atoms,  in  accordance  with  "  elec- 
tive affinities"  whose  nature  is  not  yet  understood.  A 
doctrine  of  "  nuclei "  and  a  doctrine  of  "  types  "  of  molec- 
ular structure  were  much  exploited,  and,  like  the  doc- 
trine of  compound  radicals,  became  useful  as  aids  to 
memory  and  guides  for  the  analyst,  indicating  some  of 
the  plans  of  molecular  construction,  though  by  no  means 
penetrating  the  mysteries  of  chemical  affinity.  They 

368 


THE  CENTURY'S  PROGRESS   IN   CHEMISTRY 

are  classifications  rather  than  explanations  of  chemical 
unions.  But  at  least  they  served  an  important  purpose 
in  giving  definiteness  to  the  idea  of  a  molecular  struct- 
ure built  of  atoms  as  the  basis  of  all  substances.  Now 
at  last  the  word  molecule  came  to  have  a  distinct  mean- 
ing, as  distinct  from  "atom,"  in  the  minds  of  the  gener- 
ality of  chemists,  as  it  had  had  for  Avogadro  a  third  of 
a  century  before.  Avogadro's  hypothesis  that  there  are 
equal  numbers  of  these  molecules  in  equal  volumes  of 
gases,  under  fixed  conditions,  was  revived  by  Gerhard t, 
and  a  little  later,  under  the  championship  of  Cannizzaro, 
was  exalted  to  the  plane  of  a  fixed  law.  Thenceforth 
the  conception  of  the  molecule  was  to  be  as  dominant  a 
thought  in  chemistry  as  the  idea  of  the  atom  had  be- 
come in  a  previous  epoch. 


Of  course  the  atom  itself  was  in  no  sense  displaced, 
but  Avogadro's  law  soon  made  it  plain  that  the  atom  had 
often  usurped  territory  that  did  not  really  belong  to  it. 
In  many  cases  the  chemists  had  supposed  themselves 
dealing  with  atoms  as  units  where  the  true  unit  was  the 
molecule.  In  the  case  of  elementary  gases,  such  as  hy- 
drogen and  oxygen,  for  example,  the  law  of  equal  num- 
bers of  molecules  in  equal  spaces  made  it  clear  that  the 
atoms  do  not  exist  isolated,  as  had  been  supposed.  Since 
two  volumes  of  hydrogen  unite  with  one  volume  of  oxy- 
gen to  form  two  volumes  of  water  vapor,  the  simplest 
mathematics  shows,  in  the  light  of  Avogadro's  law,  not 
only  that  each  molecule  of  water  must  contain  two  hy- 
drogen atoms  (a  point  previously  in  dispute),  but  that 
the  original  molecules  of  h}7drogen  and  oxygen  must 

269 


THE   STORY   OF  NINETEENTH-CENTURY   SCIENCE 

have  been  composed  in  each  case  of  two  atoms  —  else 
how  could  one  volume  of  oxygen  supply  an  atom  for 
every  molecule  of  two  volumes  of  water? 

What,  then,  does  this  imply  ?  Why,  that  the  ele- 
mentary atom  has  an  avidity  for  other  atoms,  a  long- 
ing for  companionship,  an  "  affinity  " — call  it  what  you 
will — which  is  bound  to  be  satisfied  if  other  atoms  are 
in  the  neighborhood.  Placed  solely  among  atoms  of 
its  own  kind,  the  oxygen  atom  seizes  on  a  fellow  oxy- 
gen atom,  and  in  all  their  mad  dancings  these  two 
mates  cling  together — possibly  revolving  about  one  an- 
other in  miniature  planetary  orbits.  Precisely  the  same 
thing  occurs  among  the  hydrogen  atoms.  But  now 
suppose  the  various  pairs  of  oxygen  atoms  come  near 
other  pairs  of  hydrogen  atoms  (under  proper  conditions 
which  need  not  detain  us  here),  then  each  oxygen  atom 
loses  its  attachment  for  its  fellow,  and  flings  itself  madly 
into  the  circuit  of  one  of  the  hydrogen  couplets,  and— 
presto ! — there  are  only  two  molecules  for  every  three 
there  were  before,  and  free  oxygen  and  hydrogen  have 
become  water.  The  whole  process,  stated  in  chemical 
phraseology,  is  summed  up  in  the  statement  that  under 
the  given  conditions  the  oxygen  atoms  had  a  greater 
affinity  for  the  hydrogen  atoms  than  for  one  another. 

As  chemists  studied  the  actions  of  various  kinds  of 
atoms,  in  regard  to  their  unions  with  one  another  to 
form  molecules,  it  gradually  dawned  upon  them  that 
not  all  elements  are  satisfied  with  the  same  number  of 
companions.  Some  elements  ask  only  one,  and  refuse 
to  take  more ;  while  others  link  themselves,  when  occa- 
sion offers,  with  two,  three,  four,  or  more.  Thus  we 
saw  that  oxygen  forsook  a  single  atom  of  its  own  kind 
and  linked  itself  with  two  atoms  of  hydrogen.  Clearly, 

270 


THE  CENTURY'S   PROGRESS    IN  CHEMISTRY 

then,  the  oxygen  atom,  like  a  creature  with  two  hands, 
is  able  to  clutch  two  other  atoms.  But  we  have  no 
proof  that  under  any  circumstances  it  could  hold  more 
than  two.  Its  affinities  seem  satisfied  when  it  has  two 
bonds.  But,  on  the  other  hand,  the  atom  of  nitrogen 
is  able  to  hold  three  atoms  of  hydrogen,  and  does  so  in 
the  molecule  of  ammonium  (NH3)  ;  while  the  carbon 
atom  can  hold  four  atoms  of  hydrogen  or  two  atoms 
of  oxygen. 

Evidently,  then,  one  atom  is  not  always  equivalent  to 
another  atom  of  a  different  kind  in  combining  powers. 
A  recognition  of  this  fact  by  Frankland  about  1852,  and 
its  further  investigation  by  others  (notably  A.  Kekule 
and  A.  S.  Couper),  led  to  the  introduction  of  the  word 
equivalent  into  chemical  terminology  in  a  new  sense, 
and  in  particular  to  an  understanding  of  the  affinities 
or  "  valency  "  of  different  elements,  which  proved  of  the 
most  fundamental  importance.  Thus  it  was  shown  that, 
of  the  four  elements  that  enter  most  prominently  into 
organic  compounds,  hydrogen  can  link  itself  with  only 
a  single  bond  to  any  other  element  —  it  has,  so  to  speak, 
but  a  single  hand  with  which  to  grasp  —  while  oxygen 
has  capacity  for  two  bonds,  nitrogen  for  three  (possi- 
bly for  five),  and  carbon  for  four.  The  words  mono- 
valent,  divalent,  trivalent,  tretravalent,  etc.,  were  coined 
to  express  this  most  important  fact,  and  the  various  ele- 
ments came  to  be  known  as  monads,  diads,  triads,  etc. 
Just  why  different  elements  should  differ  thus  in  valency 
no  one  as  yet  knows  ;  it  is  an  empirical  fact  that  they 
do.  And  once  the  nature  of  any  element  has  been  deter- 
mined as  regards  its  valency,  a  most  important  insight 
into  the  possible  behavior  of  that  element  has  been 
secured.  Thus  a  consideration  of  the  fact  that  hydro- 

271 


OF    THE 

UNIVERSITY 


THE   STORY   OF  NINETEENTH-CENTURY   SCIENCE 

gen  is  raonovalent,  while  oxygen  is  divalent,  makes  it 
plain  that  we  must  expect  to  find  no  more  than  three 
compounds  of  these  two  elements,  namely,  H — O— 
(written  HO  by  the  chemist,  and  called  hydroxyl) ; 
H— O— H  (H20,  or  water),  and  H— O— O— H  (H2O2, 
or  hydrogen  peroxide).  It  will  be  observed  that  in  the 
first  of  these  compounds  the  atom  of  oxygen  stands,  so 
to  speak,  with  one  of  its  hands  free,  eagerly  reaching 
out,  therefore,  for  another  companion,  and  hence,  in  the 
language  of  chemistry,  forming  an  unstable  compound. 
Again,  in  the  third  compound,  though  all  hands  are 
clasped,  yet  one  pair  links  oxygen  with  oxygen  ;  and 
this  also  must  be  an  unstable  union,  since  the  avidity  of 
an  atom  for  its  own  kind  is  relatively  weak.  Thus  the 
well-known  properties  of  hydrogen  peroxide  are  ex- 
plained, its  easy  decomposition,  and  the  eagerness  with 
which  it  seizes  upon  the  elements  of  other  compounds. 

But  the  molecule  of  water,  on  the  other  hand,  has  its 
atoms  arranged  in  a  state  of  stable  equilibrium,  all  their 
affinities  being  satisfied.  Each  hydrogen  atom  has  sat- 
isfied its  own  affinity  by  clutching  the  oxygen  atom; 
and  the  oxygen  atom  has  both  its  bonds  satisfied  by 
clutching  back  at  the  two  hydrogen  atoms.  Therefore 
the  trio,  linked  in  this  close  bond,  have  no  tendency  to 
reach  out  for  any  other  companion,  nor,  indeed,  any 
power  to  hold  another  should  it  thrust  itself  upon  them. 
They  form  a  "stable"  compound,  which  under  all  ordi- 
nary circumstances  will  retain  its  identity  as  a  molecule 
of  water,  even  though  the  physical  mass  of  which  it  is 
a  part  changes  its  condition  from  a  solid  to  a  gas— from 
ice  to  vapor. 

But  a  consideration  of  this  condition  of  stable  equi- 
librium in  the  molecule  at  once  suggests  a  new  question  : 

273 


THE   CENTURY'S   PROGRESS   IN    CHEMISTRY 

How  can  an  aggregation  of  atoms,  having  all  their 
affinities  satisfied,  take  any  further  part  in  chemical 
reactions?  Seemingly  such  a  molecule,  whatever  its 
physical  properties,  must  be  chemically  inert,  incapable 
of  any  atomic  readjustments.  And  so  in  point  of  fact 
it  is,  so  long  as  its  component  atoms  cling  to  one  another 
unremittingly.  But  this,  it  appears,  is  precisely  what  the 
atoms  are  little  prone  to  do.  It  seems  that  they  are 
lickle  to  the  last  degree  in  their  individual  attachments, 
and  are  as  prone  to  break  away  from  bondage  as  they  are 
to  enter  into  it.  Thus  the  oxygen  atom  which  has  just 
flung  itself  into  the  circuit  of  two  hydrogen  atoms,  the 
next  moment  flings  itself  free  again  and  seeks  new  com- 
panions. It  is  for  all  the  world  like  the  incessant  change 
of  partners  in  a  rollicking  dance. 

This  incessant  dissolution  and  reformation  of  molecules 
in  a  substance  which  as  a  whole  remains  apparently  un- 
changed was  first  fully  appreciated  by  Ste.-Claire  Deville, 
and  by  him  named  dissociation.  It  is  a  process  which 
goes  on  much  more  actively  in  some  compounds  than  in 
others,  and  very  much  more  actively  under  some  physi- 
cal conditions  (such  as  increase  of  temperature)  than  un- 
der others.  But  apparently  no  substances  at  ordinary 
temperatures,  and  no  temperature  above  the  absolute 
zero,  are  absolutely  free  from  its  disturbing  influence. 
Hence  it  is  that  molecules  having  all  the  valency  of 
their  atoms  fully  satisfied  do  not  lose  their  chemical 
activity — since  each  atom  is  momentarily  free  in  the 
exchange  of  partners,  and  may  seize  upon  different 
atoms  from  its  former  partners,  if  those  it  prefers  are 
at  hand. 

While,  however,  an  appreciation  of  this  ceaseless 
activity  of  the  atom  is  essential  to  a  proper  understand- 
s  273 


THE  STORY   OF  NINETEENTH-CENTURY   SCIENCE 

ing  of  its  chemical  efficiency,  yet  from  another  point  of 
view  the  "  saturated  "  molecule — that  is,  the  molecule 
whose  atoms  have  their  valency  all  satisfied — may  be 
thought  of  as  a  relatively  fixed  or  stable  organism. 
Even  though  it  may  presently  be  torn  down,  it  is  for 
the  time  being  a  completed  structure ;  and  a  considera- 
tion of  the  valency  of  its  atoms  gives  the  best  clew  that 
has  hitherto  been  obtainable  as  to  the  character  of  its 
architecture.  How  important  this  matter  of  architecture 
of  the  molecule — of  space  relations  of  the  atoms — may 
be  was  demonstrated  as  long  ago  as  1823,  when  Liebigand 
Wohler  proved,  to  the  utter  bewilderment  of  the  chem- 
ical world,  that  two  substances  may  have  precisely  the 
same  chemical  constitution — the  same  number  and  kind 
of  atoms — and  yet  differ  utterly  in  physical  properties. 
The  word  isomerism  was  coined  by  Berzelius  to  express 
this  anomalous  condition  of  things,  which  seemed  to 
negative  the  most  fundamental  truths  of  chemistry. 
Naming  the  condition  by  no  means  explained  it,  but 
the  fact  was  made  clear  that  something  besides  the 
mere  number  and  kind  of  atoms  is  important  in  the 
architecture  of  a  molecule.  It  became  certain  that 
atoms  are  not  thrown  together  haphazard  to  build  a 
molecule,  any  more  than  bricks  are  thrown  together 
at  random  to  form  a  house. 

How  delicate  may  be  the  gradations  of  architectural 
design  in  building  a  molecule  was  well  illustrated  about 
1850,  when  Pasteur  discovered  that  some  carbon  com- 
pounds— as  certain  sugars— can  only  be  distinguished 
from  one  another,  when  in  solution,  by  the  fact  of  their 
twisting  or  polarizing  a  ray  of  light  to  the  left  or  to 
the  right,  respectively.  But  no  inkling  of  an  explana- 
tion of  these  strange  variations  of  molecular  structure 

274 


THE   CENTURY'S   PROGRESS   IN   CHEMISTRY 

came  until  the  discovery  of  the  law  of  valency.  Then 
much  of  the  mystery  was  cleared  away ;  for  it  was 
plain  that  since  each  atom  in  a  molecule  can  hold  to 
itself  only  a  fixed  number  of  other  atoms,  complex 
molecules  must  have  their  atoms  linked  in  definite 
chains  or  groups.  And  it  is  equally  plain  that  where 
the  atoms  are  numerous,  the  exact  plan  of  grouping 
may  sometimes  be  susceptible  of  change  without  doing 
violence  to  the  law  of  valency.  It  is  in  such  cases  that 
isomerism  is  observed  to  occur. 

By  paying  constant  heed  to  this  matter  of  the  affini- 
ties, chemists  are  able  to  make  diagrammatic  pictures  of 
the  plan  of  architecture  of  any  molecule  whose  com- 
position is  known.  In  the  simple  molecule  of  water 
(H2O),  for  example,  the  two  hydrogen  atoms  must  have 
released  one  another  before  they  could  join  the  oxygen, 
and  the  manner  of  linking  must  apparently  be  that  rep- 
resented in  the  graphic  formula  H — O — II.  With  mole- 
cules composed  of  a  large  number  of  atoms,  such  graphic 
representation  of  the  scheme  of  linking  is  of  course  in- 
creasingly difficult,  yet,  with  the  affinities  for  a  guide,  it 
is  always  possible.  Of  course  no  one  supposes  that  such 
a  formula,  written  in  a  single  plane,  can  possibly  repre- 
sent the  true  architecture  of  the  molecule :  it  is  at  best 
suggestive  or  diagrammatic  rather  than  pictorial.  Never- 
theless, it  affords  hints  as  to  the  structure  of  the  mole- 
cule such  as  the  fathers  of  chemistry  would  not  have 
thought  it  possible  ever  to  attain. 


VI 

These  utterly  novel  studies  of  molecular  architecture 
may  seem  at  first  sight  to  take  from  the  atom  much  of 

275 


THE  STORY  OF  NINETEENTH-CENTURY   SCIENCE 

its  former  prestige  as  the  all-important  personage  of  the 
chemical  world.  Since  so  much  depends  upon  the  mere 
position  of  the  atoms,  it  may  appear  that  comparatively 
little  depends  upon  the  nature  of  the  atoms  themselves. 
But  such  a  view  is  incorrect,  for  on  closer  consideration 
it  will  appear  that  at  no  time  has  the  atom  been  seen  to 
renounce  its  peculiar  personality.  Within  certain  limits 
the  character  of  a  molecule  may  be  altered  by  changing 
the  positions  of  its  atoms  (just  as  different  buildings  may 
be  constructed  of  the  same  bricks),  but  these  limits  are 
sharply  defined,  and  it  would  be  as  impossible  to  exceed 
them  as  it  would  be  to  build  a  stone  building  with  bricks. 
From  first  to  last  the  brick  remains  a  brick,  whatever 
the  style  of  architecture  it  helps  to  construct;  it  never 
becomes  a  stone.  And  just  as  closely  does  each  atom 
retain  its  own  peculiar  properties,  regardless  of  its  sur- 
roundings. 

Thus,  for  example,  the  carbon  atom  may  take  part  in 
the  formation  at  one  time  of  a  diamond,  again  of  a  piece 
of  coal,  and  yet  again  of  a  particle  of  sugar,  of  wood 
fibre,  of  animal  tissue,  or  of  a  gas  in  the  atmosphere; 
but  from  first  to  last — from  glass-cutting  gem  to  in- 
tangible gas — there  is  no  demonstrable  change  whatever 
in  any  single  property  of  the  atom  itself.  So  far  as  we 
know,  its  size,  its  weight,  its  capacity  for  vibration  or 
rotation,  and  its  inherent  affinities,  remain  absolutely 
unchanged  throughout  all  these  varying  fortunes  of  po- 
sition and  association.  And  the  same  thing  is  true  of 
every  atom  of  all  of  the  sixty-odd  elementary  substances 
with  which  the  modern  chemist  is  acquainted.  Every 
one  appears  always  to  maintain  its  unique  integrity, 
gaining  nothing  and  losing  nothing. 

All  this  being  true,  it  would  seem  as  if  the  position  of 

276 


TI1E   CENTURY'S   PROGRESS   IN   CHEMISTRY 

the  Daltonian  atom  as  a  primordial  bit  of  matter,  inde- 
structible and  non-transmutable,  had  been  put  to  the 
test  by  the  chemistry  of  our  century,  and  not  found 
wanting.  Since  those  early  days  of  the  century  when 
the  electric  battery  performed  its  miracles  and  seeming- 
ly reached  its  limitations  in  the  hands  of  Davy,  many 


ROBERT  WILLIAM  BUNSEN 


new  elementary  substances  have  been  discovered,  but  no 
single  element  has  been  displaced  from  its  position  as  an 
un decomposable  body.  Kather  have  the  analyses  of  the 

277 


THE   STORY   OF   NINETEENTH-CENTURY  SCIENCE 

chemist  seemed  to  make  it  more  and  more  certain  that 
all  elementary  atoms  are  in  truth  what  John  Herschel 
called  them,  "manufactured  articles"  —  primordial, 
changeless,  indestructible. 

And  yet,  oddly  enough,  it  has  chanced  that  hand  in 
hand  with  the  experiments  leading  to  such  a  goal  have 
gone  other  experiments  and  speculations  of  exactly  the 
opposite  tenor.  In  each  generation  there  have  been 
chemists  among  the  leaders  of  their  science  who  have 
refused  to  admit  that  the  so-called  elements  are  really 
elements  at  all  in  any  final  sense,  and  who  have  sought 
eagerly  for  proof  which  might  warrant  their  scepticism. 
The  first  bit  of  evidence  tending  to  support  this  view 
was  furnished  by  an  English  physician.  Dr.  William 
Prout,  who  in  1815  called  attention  to  a  curious  relation 
to  be  observed  between  the  atomic  weight  of  the  vari- 
ous elements.  Accepting  the  figures  given  by  the  au- 
thorities of  the  time  (notably  Thomson  and  Berzelius),  it 
appeared  that  a  strikingly  large  proportion  of  the 
atomic  weights  were  exact  multiples  of  the  weight  of 
hydrogen,  and  that  others  differed  so  slightly  that  errors 
of  observation  might  explain  the  discrepancy.  Prout 
felt  that  this  could  not  be  accidental,  and  he  could  think 
of  no  tenable  explanation,  unless  it  be  that  the  atoms  of 
the  various  alleged  elements  are  made  up  of  different 
fixed  numbers  of  hydrogen  atoms.  Could  it  be  that  the 
one  true  element — the  one  primal  matter — is  hydrogen, 
and  that  all  other  forms  of  matter  are  but  compounds 
of  this  original  substance? 

Prout  advanced  this  startling  idea  at  first  tentatively, 
in  an  anonymous  publication ;  but  afterwards  he  espoused 
it  openly  and  urged  its  tenability.  Coming  just  after 
Davy's  dissociation  of  some  supposed  elements,  the  idea 


THE  CENTURY'S   PROGRESS   IN   CHEMISTRY 

proved  alluring,  and  for  a  time  gained  such  popularity 
that  chemists  were  disposed  to  round  out  the  observed 
atomic  weights  of  all  elements  into  whole  numbers. 


*  i    » 

GUSTAVE  ROBERT  KIRCHHOFP 


But  presently  renewed  determinations  of  the  atomic 
weights  seemed  to  discountenance  this  practice,  and 
Prout's  alleged  law  fell  into  disrepute.  It  was  revived, 
however,  about  1840,  by  Dumas,  whose  great  authority 
secured  it  a  respectful  hearing,  and  whose  careful  rede- 
termination  of  the  weight  of  carbon,  making  it  exactly 
twelve  times  that  of  hydrogen,  aided  the  cause, 

279 


THE   STORY   OF   NINETEENTH -CENTURY   SCIENCE 

Subsequently  Stas,  the  pupil  of  Dumas,  undertook  a 
long  series  of  determinations  of  atomic  weights,  with 
the  expectation  of  confirming  the  Proutian  hypothesis. 
But  his  results  seemed  to  disprove  the  hypothesis,  for 
the  atomic  weights  of  many  elements  differed  from 
whole  numbers  by  more,  it  was  thought,  than  the  limits 
of  error  of  the  experiments.  It  is  noteworthy,  however, 
that  the  confidence  of  Dumas  was  not  shaken,  though 
he  was  led  to  modify  the  hypothesis,  and,  in  accordance 
with  previous  suggestions  of  Clark  and  of  Marignac,  to 
recognize  as  the  primordial  element,  not  hydrogen  it- 
self, but  an  atom  half  the  weight,  or  even  one-fourth 
the  weight,  of  that  of  hydrogen,  of  which  primordial 
atom  the  hydrogen  atom  itself  is  compounded.  But 
even  in  this  modified  form  the  hypothesis  found  great 
opposition  from  experimental  observers. 

In  186i,  however,  a  novel  relation  between  the 
weights  of  the  elements  and  their  other  characteristics 
was  called  to  the  attention  of  chemists  by  Professor 
John  A.  K.  Newlands,  of  London,  who  had  noticed  that 
if  the  elements  are  arranged  serially  in  the  numerical 
order  of  their  atomic  weights,  there  is  a  curious  recur- 
rence of  similar  properties  at  intervals  of  eight  elements. 
This  so-called  "  law  of  octaves"  attracted  little  immedi- 
ate attention,  but  the  facts  it  connotes  soon  came  under 
the  observation  of  other  chemists,  notably  of  Professors 
Gustav  Hinrichs  in  America,  Dmitri  Mendeleeff  in  Rus- 
sia, and  Lothar  Meyer  in  German}^  Mendeleeff  gave 
the  discovery  fullest  expression,  expositing  it  in  1869, 
under  the  title  of  "  periodic  law." 

Though  this  early  exposition  of  what  has  since  been 
admitted  to  be  a  most  important  discovery  was  very 
fully  outlined,  the  generality  of  chemists  gave  it  little 

280 


LOUIS  JACQUES   MANDE   DAGUERRE 

From  a  daguerreotype  made  in  Paris  for  Meade  Brothers,  New  York,  flow   .n  possession  of 
Abraham  Bogardus,  New  York 


UNIVERSITT 


THE   CENTURY'S   PROGRESS   IN   CHEMISTRY 

heed  till  a  decade  or  so  later,  when  three  new  elements, 
gallium,  scandium,  and  germanium,  were  discovered, 
which,  on  being  analyzed,  were  quite  unexpectedly 
found  to  fit  into  three  gaps  which  Mendeleeff  had  left 
in  his  periodic  scale.  In  etfect,  the  periodic  law  had  en- 
abled Mendeleeff  to  predicate  the  existence  of  the  new 
elements  j^ears  before  they  were  discovered.  Surely  a 
system  that  leads  to  such  results  is  no  mere  vagary.  So 
very  soon  the  periodic  law  took  its  place  as  one  of  the 
most  important  generalizations  of  chemical  science. 

This  law  of  periodicity  was  put  forward  as  an  expres- 
sion of  observed  relations  independent  of  hypothesis; 
but  of  course  the  theoretical  bearings  of  these  facts 
could  not  be  overlooked.  As  Professor  J.  H.  Gladstone 
has  said,  it  forces  upon  us  "  the  conviction  that  the  ele. 
ments  are  not  separate  bodies  created  without  reference 
to  one  another,  but  that  they  have  been  originally  fash- 
ioned, or  have  been  built  up,  from  one  another,  accord- 
ing to  some  general  plan."  It  is  but  a  short  step  from 
that  proposition  to  the  Proutian  hypothesis. 

But  the  atomic  weights  are  not  alone  in  suggesting 
the  compound  nature  of  the  alleged  elements.  Evi- 
dence of  a  totally  different  kind  has  contributed  to  the 
same  end,  from  a  source  that  could  hardly  have  been 
imagined  when  the  Proutian  hypothesis  was  formulated, 
through  the  addition  of  a  novel  weapon  to  the  arma- 
mentarium of  the  chemist— the  spectroscope.  The  per- 
fection of  this  instrument,  in  the  hands  of  two  German 
scientists,  Gustav  Robert  Kirchhoff  and  Robert  Wilhelm 
Bunsen,  came  about  through  the  investigation,  towards 
the  middle  of  the  century,  of  the  meaning  of  the  dark 
lines  which  had  been  observed  in  the  solar  spectrum  by 
Fraunhofer  as  early  as  1815,  and  by  Wollaston  a  decade 

283 


THE   STORY   OF  NINETEENTH-CENTURY   SCIENCE 

earlier.  It  was  suspected  by  Stokes  and  by  Fox  Talbot 
in  England,  but  iirst  brought  to  demonstration  by  Kirch- 
hoff  and  Bunsen,  that  these  lines,  which  were  known  to 
occupy  definite  positions  in  the  spectrum,  are  really  in- 
dicative of  particular  elementary  substances.  By  means 
of  the  spectroscope,  which  is  essentially  a  magnifying 
lens  attached  to  a  prism  of  glass,  it  is  possible  to  locate 
the  lines  with  great  accuracy,  and  it  was  soon  shown 
that  here  was  a  new  means  of  chemical  analysis  of  the 
most  exquisite  delicacy.  It  was  found,  for  example, 
that  the  spectroscope  could  detect  the  presence  of  a 
quantity  of  sodium  so  infinitesimal  as  the  one  two- 
hundred-thousandth  of  a  grain.  But  what  was  even  more 
important,  the  spectroscope  put  no  limit  upon  the  dis- 
tance of  location  of  the  substance  it  tested,  provided 
only  that  sufficfent  light  came  from  it.  The  experi- 
ments it  recorded  might  be  performed  in  the  sun,  or  in 
the  most  distant  stars  or  nebulae ;  indeed,  one  of  the 
earliest  feats  of  the  instrument  was  to  wrench  from  the 
sun  the  secret  of  his  chemical  constitution. 

To  render  the  utility  of  the  spectroscope  complete, 
however,  it  was  necessary  to  link  with  it  another  new 
chemical  agency,  namely,  photography.  This  now  fa- 
miliar process  is  based  on  the  property  of  light  to  de- 
compose certain  unstable  compounds  of  silver,  and  thus 
alter  their  chemical  composition.  We  have  seen  that 
Daw  and  Wedgwood  barely  escaped  the  discovery  of 
the  value  of  the  photographic  method.  Their  successors 
quite  overlooked  it  until  about  1826,  when  Louis  J.  M. 
Daguerre,  the  French  chemist,  took  the  matter  in  hand, 
and  after  many  years  of  experimentation  brought  it  to 
relative  perfection  in  1839,  in  which  year  the  famous 
daguerreotype  first  brought  the  matter  to  popular  at- 

284 


TliK  CENTURY'S   PROGRESS   IN  CHEMISTRY 

tention.  In  the  same  year  Mr.  Fox  Talbot  read  a  paper 
on  the  subject  before  the  Koyal  Society,  and  soon  after, 
wards  the  efforts  of  Herschel  and  numerous  other  natu- 
ral philosophers  contributed  to  the  advancement  of  the 
new  method. 


JOHN    W.    DRAPER 


In  1843  Dr.  John  W.  Draper,  the  famous  English- 
American  chemist  and  physiologist,  showed  that  by 
photography  the  Fraunhofer  lines  in  the  solar  spectrum 
might  be  mapped  with  absolute  accuracy ;  also  proving 
that  the  silvered  film  revealed  many  lines  invisible  to 
the  unaided  eye.  The  value  of  this  method  of  observa- 
tion was  recognized  at  once,  and,  as  soon  as  the  spectro- 

285 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

scope  was  perfected,  the  photographic  method,  in  con- 
junction with  its  use,  became  invaluable  to  the  chemist. 
By  this  means  comparisons  of  spectra  may  be  made 
with  a  degree  of  accuracy  not  otherwise  obtainable ; 
and  in  case  of  the  stars,  whole  clusters  of  spectra  may 
be  placed  on  record  at  a  single  observation. 

As  the  examination  of  the  sun  and  stars  proceeded, 
chemists  were  amazed  or  delighted,  according  to  their 
various  preconceptions,  to  witness  the  proof  that  many 
familiar  terrestrial  elements  are  to  be  found  in  the  ce- 
lestial bodies.  But  what  perhaps  surprised  them  most 
was  to  observe  the  enormous  preponderance  in  the  si- 
deral  bodies  of  the  element  hj^drogen.  Not  only  are 
there  vast  quantities  of  this  element  in  the  sun's  atmos- 
phere, but  some  other  suns  appeared  to  show  hydrogen 
lines  almost  exclusively  in  their  spectra.  Presently  it 
appeared  that  the  stars  of  which  this  is  true  are  those 
white  stars,  such  as  Sirius,  which  had  been  conjectured 
to  be  the  hottest ;  whereas  stars  that  are  only  red-hot, 
like  our  sun,  show  also  the  vapors  of  many  other  ele- 
ments, including  iron  and  other  metals. 

In  1878  Mr.  J.  Norman  Lockyer,  in  a  paper  before 
the  Royal  Society,  called  attention  to  the  possible  sig- 
nificance of  this  series  of  observations.  He  urged  that 
the  fact  of  the  sun  showing  fewer  elements  than  are  ob- 
served here  on  the  cool  earth,  while  stars  much  hotter 
than  the  sun  show  chiefly  one  element,  and  that  one 
hydrogen,  the  lightest  of  known  elements,  seemed  to  give 
color  to  the  possibility  that  our  alleged  elements  are 
really  compounds,  which  at  the  temperature  of  the  hot- 
test stars  may  be  decomposed  into  hydrogen,  the  latter 
"  element "  itself  being  also  doubtless  a  compound,  which 
might  be  resolved  under  yet  more  trying  conditions. 

286 


THE   CENTURY'S   PROGRESS   IN   CHEMISTRY 

Here,  then,  was  what  might  be  termed  direct  experi- 
mental evidence  for  the  hypothesis  of  Prout.  Unfortu- 
nately, however,  it  is  evidence  of  a  kind  which  only  a 
few  experts  are  competent  to  discuss — so  very  delicate  a 
matter  is  the  spectral  analysis  of  the  stars.  What  is 
still  more  unfortunate,  the  experts  do  not  agree  among 
themselves  as  to  the  validity  of  Mr.  Lockyer's  conclu- 
sions. Some,  like  Professor  Crookes,  have  accepted 
them  with  acclaim,  hailing  Lockyer  as  "  the  Darwin  of 
the  inorganic  world,"  while  others  have  sought  a  differ- 
ent explanation  of  the  facts  he  brings  forward.  As  yet 
it  cannot  be  said  that  the  controversy  has  been  brought 
to  final  settlement.  Still,  it  is  hardly  to  be  doubted 
that  now,  since  the  periodic  law  has  seemed  to  join 
hands  with  the  spectroscope,  a  belief  in  the  compound 
nature  of  the  so-called  elements  is  rapidly  gaining 
ground  among  chemists.  More  and  more  general  be- 
comes the  belief  that  the  Daltonian  atom  is  really  a 
compound  radical,  and  that  back  of  the  seeming  di- 
versity of  the  alleged  elements  is  a  single  unique  form 
of  primordial  matter.  But  it  should  not  be  forgotten 
that  this  view,  whatever  its  attractiveness,  still  lurks  in 
the  domain  of  theory.  There  is  no  proof  that  the  Dal- 
tonian atom  has  yet  been  divided  in  the  laboratory. 


CHAPTER  IX 
THE  CENTURY'S  PROGRESS  IN  BIOLOGY 

I 

THEORIES    OF    ORGANIC    EVOLUTION 

WHEN  Coleridge  said  of  Humphry  Davy  that  he  might 
have  been  the  greatest  poet  of  his  time  had  he  not 
chosen  rather  to  be  the  greatest  chemist,  it  is  possible 
that  the  enthusiasm  o-f  the  friend  outweighed  the  cau- 
tion of  the  critic.  But  however  that  may  be,  it  is  be- 
yond dispute  that  the  man  who  actually  was  the  great- 
est poet  of  that  time  might  easily  have  taken  the  very 
highest  rank  as  a  scientist  had  not  the  Muse  distracted 
his  attention.  Indeed,  despite  these  distractions,  Johann 
Wolfgang  von  Goethe  achieved  successes  in  the  field  of 
pure  science  that  would  insure  permanent  recognition 
for  his  name  had  he  never  written  a  stanza  of  poetry. 
Such  is  the  versatility  that  marks  the  highest  genius. 

It  was  in  1790  that. Goethe  published  the  work  that 
laid  the  foundations  of  his  scientific  reputation — the 
work  on  the  Metamorphoses  of  Plants,  in  which  he  ad- 
vanced the  novel  doctrine  that  all  parts  of  the  flower  are 
modified  or  metamorphosed  leaves.  This  was  followed 
presently  by  an  extension  of  the  doctrine  of  metamor- 

288 


• 

THE   CENTURY'S    PROGRESS'  IN .  BloLOU-Y 

phosis  to  the  animal  kingdom,  in  the  doctrine  which 
Goethe  and  Oken  advanced  independently,  that  the  ver- 
tebrate skull  is  essentially  a  modified  and  developed  ver- 
tebra. These  were  conceptions  worthy  of  a  poet;  im- 
possible, indeed,  for  any  mind  that  had  not  the  poetic 
faculty  of  correlation.  But  in  this  case  the  poet's  vision 
was  prophetic  of  a  future  view  of  the  most  prosaic  sci- 
ence. The  doctrine  of  metamorphosis  of  parts  soon 
came  to  be  regarded  as  a  fundamental  feature  in  the 
science  of  living  things. 

But  the  doctrine  had  implications  that  few  of  its 
early  advocates  realized.  If  all  the  parts  of  a  flower — 
sepal,  petal,  stamen,  pistil,  with  their  countless  devia- 
tions of  contour  and  color — are  but  modifications  of  the 
leaf,  such  modification  implies  a  marvellous  differentia- 
tion and  development.  To  assert  that  a  stamen  is  a 
metamorphosed  leaf  means,  if  it  means  anything,  that  in 
the  long  sweep  of  time  the  leaf  has  by  slow  or  sudden 
gradations  changed  its  character  through  successive 
generations,  until  the  offspring,  so  to  speak,  of"  a  true 
leaf  has  become  a  stamen.  But  if  such  a  metamorphosis 
as  this  is  possible — if  the  seemingly  wide  gap  between 
leaf  and  stamen  may  be  spanned  by  the  modification  of 
a  line  of  organisms — where  does  the  possibility  of  modi- 
fication of  organic  type  find  its  bounds?  Why  may 
not  the  modification  of  parts  go  on  along  devious  lines 
until  the  remote  descendants  of  an  organism  are  utterly 
unlike  that  organism?  Why  may  we  not  thus  account 
for  the  development  of  various  species  of  beings  all 
sprung  from  one  parent  stock?  That  too  is  a  poet's 
dream;  but  is  it  only  a  dream?  Goethe  thought  not. 
Out  of  his  studies  of  metamorphosis  of  parts  there  grew 
in  his  mind  the  belief  that  the  multitudinous  species  of 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

plants  and  animals  about  us  have  been  evolved  from 
fewer  and  fewer  earlier  parent  types,  like  twigs  of  a 
giant  tree  drawing  their  nurture  from  the  same  primal 


ERASMUS  DATIWIN 

root.     It  was  a  bold  and  revolutionary  thought;   and 
the  world  regarded  it  as  but  the  vagary  of  a  poet. 

Just  at  the  time  when  this  thought  was  taking  form 
in  Goethe's  brain,  the  same  idea  was  germinating  in  the 
mind  of  another  philosopher,  an  Englishman  of  interna- 
tional fame,  Dr.  Erasmus  Darwin,  who,  while  he  lived, 
enjoyed  the  widest  popularity  as  a  poet,  the  rhymed 
couplets  of  his  Botanic  Garden  being  quoted  every- 

290 


THE  CENTURY'S   PROGRESS   IN  BIOLOGY 

where  with  admiration.  And  posterity,  repudiating  the 
verse  which  makes  the  body  of  the  book,  yet  grants 
permanent  value  to  the  book  itself,  because,  forsooth, 
its  copious  explanatory  footnotes  furnish  an  outline  of 
the  status  of  almost  every  department  of  science  of 
the  time. 

But  even  though  he  lacked  the  highest  art  of  the  versi- 
fier, Darwin  had,  beyond  perad venture,  the  imagination 
of  a  poet  coupled  with  profound  scientific  knowledge ; 
and  it  was  his  poetic  insight,  correlating  organisms  seem- 
ingly diverse  in  structure,  and  imbuing  the  lowliest 
flower  with  a  vital  personality,  which  led  him  to  sus- 
pect that  there  are  no  lines  of  demarcation  in  nature. 
"  Can  it  be,"  he  queries,  "  that  one  form  of  organism 
has  developed  from  another ;  that  different  species  are 
really  but  modified  descendants  of  one  parent  stock?" 
The  alluring  thought  nestled  in  his  mind  and  was  nurt- 
ured there,  and  grew  into  a  fixed  belief,  which  was 
given  fuller  expression  in  his  Zoonomia,  and  in  the 
posthumous  Temple  of  Nature.  But  there  was  little 
proof  of  its  validity  forthcoming  that  could  satisfy  any 
one  but  a  poet,  and  when  Erasmus  Darwin  died,  in  1802, 
the  idea  of  transmutation  of  species  was  still  but  an  un- 
substantiated dream. 

It  was  a  dream,  however,  which  was  not  confined  to 
Goethe  and  Darwin.  Even  earlier  the  idea  had  come 
more  or  less  vaguely  to  another  great  dreamer — and 
worker — of  Germany,  Immanuel  Kant,  and  to  several 
great  Frenchmen,  including  De  Maillet,  Maupertuis, 
Robinet,  and  the  famous  naturalist  Buffon — a  man  who 
had  the  imagination  of  a  poet,  though  his  message  was 
couched  in  most  artistic  prose.  Not  long  after  the  mid- 
dle of  the  eighteenth  century  Buffon  had  put  forward 


TUP:   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

the  idea  of  transmutation  of  species,  and  he  reiterated 
it  from  time  to  time  from  then  on  till  his  death  in  1788. 
But  the  time  was  not  yet  ripe  for  the  idea  of  transmu- 
tation of  species  to  burst  its  bonds. 

And  yet  this  idea,  in  a  modified  or  undeveloped  form, 
had  taken  strange  hold  upon  the  generation  that  was 
upon  the  scene  at  the  close  of  the  eighteenth  century. 
Vast  numbers  of  hitherto  unknown  species  of  animals 
had  been  recently  discovered  in  previously  unexplored 
regions  of  the  globe,  and  the  wise  men  were  sorely  puz- 
zled to  account  for  the  disposal  of  all  of  these  at  the 
time  of  the  Deluge.  It  simplified  matters  greatly  to 
suppose  that  many  existing  species  had  been  developed 
since  the  episode  of  the  Ark  by  modification  of.  the 
original  pairs.  The  remoter  bearings  of  such  a  theory 
were  overlooked  for  the  time,  and  the  idea  that  Amer- 
ican animals  and  birds,  for  example,  were  modified 
descendants  of  Old  World  forms — the  jaguar  of  the 
leopard,  the  puma  of  the  lion,  and  so  on — became  a  cur- 
rent belief  with  that  class  of  humanity  who  accept  al- 
most any  statement  as  true  that  harmonizes  with  their 
prejudices,  without  realizing  its  implications. 

Thus  it  is  recorded  with  eclat  that  the  discovery  of 
the  close  proximity  of  America  at  the  northwest  with 
Asia  removes  all  difficulties  as  to  the  origin  of  the 
Occidental  faunas  and  floras,  since  Oriental  species 
might  easily  have  found  their  way  to  America  on  the 
ice,  and  have  been  modified  as  we  find  them  by  "  the 
well-known  influence  of  climate."  And  the  persons  who 
gave  expression  to  this  idea  never  dreamed  of  its  real 
significance.  In  truth,  here  was  the  doctrine  of  evolu- 
tion in  a  nutshell,  and,  because  its  ultimate  bearings 
were  not  clear,  it  seemed  the  most  natural  of  doctrines. 

292 


T11E   CENTURY'S   PROGRESS   IN   BIOLOGY 

But  most  of  the  persons  who  advanced  it  would  have 
turned  from  it  aghast  could  they  have  realized  its  im- 
port. As  it  was,  however,  only  here  and  there  a  man 
like  Buff  on  reasoned  far  enough  to  inquire  what  might 
be  the  limits  of  such  assumed  transmutation ;  and  only 
here  and  there  a  Darwin  or  a  Goethe  reached  the  con- 
viction that  there  are  no  limits. 


ii 

And  even  Goethe  and  Darwin  had  scarcely  passed  be- 
yond that  tentative  stage  of  conviction  in  which  they 
held  the  thought  of  transmutation  of  species  as  an  ancil- 
lary belief,  not  yet  ready  for  full  exposition  There 
was  one  of  their  contemporaries,  however,  who,  holding 
the  same  conception,  was  moved  to  give  it  full  explica- 
tion. This  was  the  friend  and  disciple  of  Buffon,  Jean 
Baptiste  de  Lamarck.  Possessed  of  the  spirit  of  a  poet 
and  philosopher,  this  great  Frenchman  had  also  the  widest 
range  of  technical  knowledge,  covering  the  entire  field 
of  animate  nature.  The  first  half  of  his  long  life  was 
devoted  chiefly  to  botany,  in  which  he  attained  high 
distinction.  Then,  just  at  the  beginning  of  our  cen- 
tury, he  turned  to  zoology,  in  particular  to  the  lower 
forms  of  animal  life.  Studying  these  lowly  organisms, 
existing  and  fossil,  he  was  more  and  more  impressed 
with  the  gradations  of  form  everywhere  to  be  seen  ; 
the  linking  of  diverse  families  through  intermediate 
ones;  and  in  particular  with  the  predominance  of  low 
types  of  life  in  the  earlier  geological  strata.  Called  upon 
constantly  to  classify  the  various  forms  of  life  in  the 
course  of  his  systematic  writings,  he  found  it  more  and 
more  difficult  to  draw  sharp  lines  of  demarcation,  and  at 

293 


THE   STORY'    OF   NINETEENTH-CENTURY    SCIENCE 

last  the  suspicion  long  harbored  grew  into  a  settled  con- 
viction that  there  is  really  no  such  thing  as  a  species  of 
organism  in  nature ;  that  "  species  "  is  a  figment  of  the 


JEAN   BAPTISTE   DE   LAMARCK 

human  imagination,  whereas  in  nature  there  are  only 
individuals. 

That  certain  sets  of  individuals  are  more  like  one  an- 
other than  like  other  sets  is  of  course  patent,  but  this 

294 


THE  CENTURY'S   PROGRESS   IN   BIOLOGY 

only  means,  said  Lamarck,  that  these  similar  groups 
have  had  comparatively  recent  common  ancestors,  while 
dissimilar  sets  of  beings  are  more  remotely  related  in 
consanguinity.  But  trace  back  the  lines  of  descent  far 
enough,  and  all  will  culminate  in  one  original  stock. 
All  forms  of  life  whatsoever  are  modified  descendants 
of  an  original  organism.  From  lowest  to  highest,  then, 
there  is  but  one  race,  one  species,  just  as  all  the  mul- 
titudinous branches  and  twigs  from  one  root  are  but 
one  tree.  For  purposes  of  convenience  of  description, 
we  may  divide  organisms  into  orders,  families,  genera, 
species,  just  as  we  divide  a  tree  into  root,  trunk, 
branches,  twigs,  leaves  ;  but  in  the  one  case,  as  in  the 
other,  the  division  is  arbitrary  and  artificial. 

In  Philosophic  Zoologique  (1809),  Lamarck  first  ex- 
plicitly formulated  his  ideas  as  to  the  transmutation  of 
species,  though  he  had  outlined  them  as  early  as  1801. 
In  this  memorable  publication  not  only  did  he  state  his 
belief  more  explicitly  and  in  fuller  detail  than  the  idea 
had  been  expressed  by  any  predecessor,  but  he  took  an- 
other long  forward  step,  carrying  him  far  beyond  all  his 
forerunners  except  Darwin,  in  that  he  made  an  attempt 
to  explain  the  way  in  which  the  transmutation  of  spe- 
cies had  been  brought  about.  The  changes  have  been 
wrought,  he  said,  through  the  unceasing  efforts  of  each 
organism  to  meet  the  needs  imposed  upon  itfby  its  envi- 
ronment. Constant  striving  means  the  constant  use  of 
certain  organs,  and  such  use  leads  to  the  development 
of  those  organs.  Thus  a  bird  running  by  the  sea-shore 
is  constantly  tempted  to  wade  deeper  and  deeper  in 
pursuit  of  food;  its  incessant  efforts  tend  to  develop 
its  legs,  in  accordance  with  the  observed  principle  that 
the  use  of  any  organ  tends  to  strengthen  and  develop  it. 

395 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

But  such  slightly  increased  development  of  the  legs  is 
transmitted  to  the  offspring  of  the  bird,  which  in  turn 
develops  its  already  improved  legs  by  its  individual  ef- 
forts, and  transmits  the  improved  tendency.  Generation 
after  generation  this  is  repeated,  until  the  sum  of  the 
infinitesimal  variations,  all  in  the  same  direction,  results 
in  the  production  of  the  long-legged  wading-bird.  In 
a  similar  way,  through  individual  effort  and  transmitted 
tendency,  all  the  diversified  organs  of  all  creatures  have 
been  developed — the  fin  of  the  fish,  the  wing  of  the  bird, 
the  hand  of  man  ;  nay,  more,  the  fish  itself,  the  bird,  the 
man,  even.  Collectively  the  organs  make  up  the  entire 
organism;  and  what  is  true  of  the  individual  organs 
must  be  true  also  of  their  ensemble,  the  living  being. 

Whatever  might  be  thought  of  Lamarck's  explanation 
of  the  cause  of  transmutation  —  which  really  was  that 
already  suggested  by  Erasmus  Darwin  — the  idea  of  the 
evolution  for  which  he  contended  was  but  the  logical 
extension  of  the  conception  that  American  animals  are 
the  modified  and  degenerated  descendants  of  European 
animals.  But  people  as  a  rule  are  little  prone  to  follow 
ideas  to  their  logical  conclusions,  and  in  this  case  the 
conclusions  were  so  utterly  opposed  to  the  proximal 
bearings  of  the  idea  that  the  whole  thinking  world 
repudiated  them  with  acclaim.  The  very  persons  who 
had  most  eagerly  accepted  the  idea  of  transmutation  of 
European  species  into  American  species,  and  similar  lim- 
ited variations  through  changed  environment,  because 
of  the  relief  thus  given  the  otherwise  overcrowded  Ark, 
were  now  foremost  in  denouncing  such  an  extension  of 
the  doctrine  of  transmutation  as  Lamarck  proposed. 

And,  for  that  matter,  the  leaders  of  the  scientific  world 
were  equally  antagonistic  to  the  Lamarckian  hypothesis, 

396 


THE   CENTURY'S   PROGRESS   IN   BIOLOGY 

Cuvier  in  particular,  once  the  pupil  of  Lamarck,  but  now 
his  colleague,  and  in  authority  more  than  his  peer,  stood 
out  against  the  transmutation  doctrine  with  all  his  force. 
He  argued  for  the  absolute  fixity  of  species,  bringing  to 
bear  the  resources  of  a  mind  which,  as  a  mere  repository 
of  facts,  perhaps  never  was  excelled.  As  a  final  and 
tangible  proof  of  his  position,  he  brought  forward  the 
bodies  of  ibises  that  had  been  embalmed  by  the  ancient 
Egyptians,  and  showed  by  comparison  that  these  do  not 
differ  in  the  slightest  particular  from  the  ibises  that  visit 
the  Kile  to-day.  Lamarck  replied  that  this  proved  noth- 
ing except  that  the  ibis  had  become  perfectly  adapted 
to  its  Egyptian  surroundings  in  an  early  day,  historically 
speaking,  and  that  the  climatic  and  other  conditions  of 
the  Nile  Valley  had  not  since  then  changed.  His  the- 
ory, he  alleged,  provided  for  the  stability  of  species 
under  fixed  conditions  quite  as  well  as  for  transmuta- 
tion under  varying  conditions. 

But,  needless  to  say,  the  popular  verdict  lay  with  Cu- 
vier; talent  won  for  the  time  against  genius,  and  La- 
marck was  looked  upon  as  as  impious  visionary.  His 
faith  never  wavered,  however.  He  believed  that  he  had 
gained  a  true  insight  into  the  processes  of  animate  nat- 
ure, and  he  reiterated  his  hypotheses  over  and  over,  par- 
ticularly in  the  introduction  to  his  Histoire  naturelle  des 
Animaux  sans  Vertehres,  in  1815,  and  in  his  Systeme  des 
Connaissances positives  de  Vllomme,  in  1820.  He  lived 
on  till  1829,  respected  as  a  naturalist,  but  almost  unrec- 
ognized as  a  prophet. 

in 

While  the  names  of  Darwin  and  Goethe,  and  in  par- 
ticular that  of  Lamarck,  must  always  stand  out  in  high 

397 


THE   STORY   OF   NINETEENTH-CENTURY  SCIENCE 

relief  in  this  generation  as  the  exponents  of  the  idea  of 
transmutation  of  species,  there  are  a  few  others  which 
must  not  be  altogether  overlooked  in  this  connection. 
Of  these  the  most  conspicuous  is  that  of  Gottfried  Rein- 
hold  Treviranus,  a  German  naturalist  physician,  profess- 
or of  mathematics  in  the  lyceum  at  Bremen. 

It  was  an  interesting  coincidence  that  Treviranus 
should  have  published  the  first  volume  of  his  Biologie, 
oder  Philosophie  der  lebenden  Natur,  in  which  his  views 
on  the  transmutation  of  species  were  expounded,  in  1802, 
the  same  twelvemonth  in  which  Lamarck's  first  exposi- 
tion of  the  same  doctrine  appeared  in  his  RecJierches  sur 
V  Organisation  des  Corps  Vivants.  It  is  singular,  too, 
that  Lamarck,  in  his  Ilydrogeologie  of  the  same  date, 
should  independently  have  suggested  "  biology  "  as  an 
appropriate  word  to  express  the  general  science  of  living 
things.  It  is  significant  of  the  tendency  of  thought  of 
the  time  that  the  need  of  such  a  unifying  word  should 
have  presented  itself  simultaneously  to  independent 
thinkers  in  different  countries. 

That  same  memorable  year,  Lorenz  Oken,  another 
philosophical  naturalist,  professor  in  the  University  of 
Zurich,  published  the  preliminary  outlines  of  his  Phi- 
losophie der  Natur,  which,  as  developed  through  later 
publications,  outlined  a  theory  of  spontaneous  generation 
and  of  evolution  of  species.  Thus  it  appears  that  this 
idea  was  germinating  in  the  minds  of  several  of  the 
ablest  men  of  the  time  during  the  first  decade  of  our 

O 

century.  But  the  singular  result  of  their  various  expli- 
cations was  to  give  sudden  check  to  that  undercurrent 
of  thought  which  for  some  time  had  been  setting  tow- 
ards this  conception.  As  soon  as  it  was  made  clear 
whither  the  concession  that  animals  may  be  changed  by 


THE   CENTURY'S   PROGRESS   IN  BIOLOGY.. 

their  environment  must  logically  trend,  the  recoil  from 
the  idea  was  instantaneous  and  fervid.  Then  for  a  gen- 
eration Cuvier  was  almost  absolutely  dominant,  and  his 
verdict  was  generally  considered  final. 


ETIENNE   GEOFFKOY   SAINT-HILAIHE 

There  was,  indeed,  one  naturalist  of  authority  in 
France  who  had  the  hardihood  to  stand  out  against 
Cuvier  and  his  school,  and  who  was  in  a  position  to 
gain  a  hearing,  though  by  no  means  to  divide  the  fol- 

* 


THE   STORY  OF   NLNETEENTLl-CENTURY   SCIENCE 

lowing.  This  was  Etienne  Geoffrey  Saint-Hilaire,  the 
famous  author  of  the  Philosophic  Anatomique,  and  for 
many  years  the  colleague  of  Lamarck  at  the  Jardin  des 
Plantes.  Like  Goethe,  Geoffroy  was  pre-eminently  an 
anatomist,  and,  like  the  great  German,  he  had  early 
been  impressed  with  the  resemblances  between  the  anal- 
ogous organs  of  different  classes  of  beings.  He  con- 
ceived the  idea  that  an  absolute  unity  of  type  prevails 
throughout  organic  nature  as  regards  each  set  of  organs. 
Out  of  this  idea  grew  his  gradually  formed  belief  that 
similarity  of  structure  might  imply  identity  of  origin— 
that,  in  short,  one  species  of  animal  might  have  devel- 
oped from  another. 

Geoffroy's  grasp  of  this  idea  of  transmutation  was  by 
no  means  so  complete  as  that  of  Lamarck,  and  he  seems 
never  to  have  fully  determined  in  his  own  mind  just 
what  might  be  the  limits  of  such  development  of  species. 
Certainly  he  nowhere  includes  all  organic  creatures  in 
one  line  of  descent,  as  Lamarck  had  done;  nevertheless 
he  held  tenaciously  to  the  truth  as  he  saw  it,  in  open  op- 
position to  Cuvier,  with  whom  he  held  a  memorable  de- 
bate at  the  Academy  of  Sciences  in  1830 — the  debate 
which  so  aroused  the  interest  and  enthusiasm  of  Goethe, 
but  which,  in  the  opinion  of  nearly  every  one  else,  re- 
sulted in  crushing  defeat  for  Geoffroy,  and  brilliant, 
seemingly  final,  victory  for  the  advocate  of  special  cre- 
ation and  the  fixity  of  species. 

With  that  all  ardent  controversy  over  the  subject 
seemed  to  end,  and  for  just  a  quarter  of  a  century  to 
come  there  was  published  but  a  single  argument  for 
transmutation  of  species  which  attracted  any  general  at- 
tention whatever.  This  oasis  in  a  desert  generation  was 
a  little  book  called  Vestiges  of  the  Natural  History  of 

300' 


THE   CENTURY'S  PROGRESS   IN   BIOLOGY 

Creation,  which  appeared  anonymously  in  England  in 
1844,  and  which  passed  through  numerous  editions,  and 
was  the  subject  of  no  end  of  abusive  and  derisive  com- 
ment. The  authorship  of  this  book  remained  for  forty 
years  a  secret,  but  it  is  now  conceded  to  have  been  the 
work  of  Robert  Chambers,  the  well-known  English 
author  and  publisher.  The  book  itself  is  remarkable  as 
being  an  avowed  and  unequivocal  exposition  of  a  gener- 
al doctrine  of  evolution,  its  view  being  as  radical  and 
comprehensive  as  that  of  Lamarck  himself.  But  it  was 
a  resume  of  earlier  efforts  rather  than  a  new  departure, 
to  say  nothing  of  its  technical  shortcomings,  and,  while 
it  aroused  bitter  animadversions,  and  cannot  have  been 
without  effect  in  creating  an  undercurrent  of  thought  in 
opposition  to  the  main  trend  of  opinion  of  the  time,  it 
can  hardly  be  said  to  have  done  more  than  that.  In- 
deed, some  critics  have  denied  it  even  this  merit.  After 
its  publication,  as  before,  the  conception  of  transmuta- 
tion of  species  remained  in  the  popular  estimation,  both 
lay  and  scientific,  an  almost  forgotten  "  heresy." 

It  is  true  that  here  and  there  a  scientist  of  greater  or 
less  repute — as  Yon  Buch,  Meckel,  and  Yon  Baer  in 
Germany,  Bory  Saint  Yincent  in  France,  Wells,  Grant, 
and  Matthew  in  England,  and  Leidy  in  America — had 
expressed  more  or  less  tentative  dissent  from  the  doc- 
trine of  special  creation  and  immutability  of  species,  but 
their  unaggressive  suggestions,  usually  put  forward  in 
obscure  publications,  and  incidentally,  were  utterly  over- 
looked and  ignored.  And  so,  despite  the  scientific  ad- 
vances along  many  lines  at  the  middle  of  the  century, 
the  idea  of  the  transmutability  of  organic  races  had  no 
such  prominence,  either  in  scientific  or  unscientific  cir- 
cles, as  it  had  acquired  fifty  years  before.  Special  cre- 

801 


THE   STORY  OF  NINETEENTHrCENTURY  SCIENCE 

ation  held  the  day,  apparently  unchallenged  and  unop- 
posed. 

IV 

But  even  at  this  time  the  fancied  security  of  the  spe- 
cial-creation hypothesis  was  by  no  means  real.  Though 
it  seemed  so  invincible,  its  real  position  was  that  of  an 
apparently  impregnable  fortress  beneath  which,  all  un- 
beknown to  the  garrison,  a  powder-mine  has  been  dug 
and  lies  ready  for  explosion.  For  already  there  existed 
in  the  secluded  work-room  of  an  English  naturalist,  a 
manuscript  volume  and  a  portfolio  of  notes  which  might 
have  sufficed,  if  given  publicity,  to  shatter  the  entire 
structure  of  the  special-creation  hypothesis.  The  natu- 
ralist who,  by  dint  of  long  and  patient  effort,  had  con- 
structed this  powder-mine  of  facts  was  Charles  Robert 
Darwin,  grandson  of  the  author  of  Zoonomia. 

As  long  ago  as  July  1,  1837,  young  Darwin,  then 
twenty-eight  years  of  age,  had  opened  a  private  jour- 
nal, in  which  he  purposed  to  record  all  facts  that 
came  to  him  which  seemed  to  have  any  bearing  on 
the  moot  point  of  the  doctrine  of  transmutation  of  spe- 
cies. Four  or  five  years  earlier,  during  the  course  of 
that  famous  trip  around  the  world  with  Admiral  Fitz- 
roy,  as  naturalist  to  the  Beagle,  Darwin  had  made  the 
personal  observations  which  first  tended  to  shake  his  be- 
lief in  the  fixity  of  species.  In  South  America,  in  the 
Pampean  formation,  he  had  discovered  "  great  fossil  an- 
imals covered  with  armor  like  that  on  the  existing  arma- 
dillos," and  had  been  struck  with  this  similarity  of  type 
between  ancient  and  existing  faunas  of  the  same  region. 
He  was  also  greatly  impressed  by  the  manner  in  which 
closely  related  species  of  animals  were  observed  to  re- 

302 


THE   CENTURY'S   PROGRESS   IN   BIOLOGY 

place  one  another  as  he  proceeded  southward  over  the 
continent ;  and  "  by  the  South  American  character  of 
most  of  the  productions  of  the  Galapagos  Archipelago, 
and  more  especially  by  the  manner  in  which  they  differ 
slightly  on  each  island  of  the  group,  none  of  the  islands 
appearing  to  be  very  ancient  in  a  geological  sense." 

At  first  the  full  force  of  these  observations  did  not 
strike  him ;  for,  under  sway  of  LyelPs  geological  con- 
ceptions, he  tentatively  explained  the  relative  absence 
of  life  on  one  of  the  Galapagos  Islands  by  suggesting 
that  perhaps  no  species  had  been  created  since  that  isl- 
and arose.  But  gradually  it  dawned  upon  him  that 
such  facts  as  he  had  observed  "  could  only  be  explained 
on  the  supposition  that  species  gradually  become  modi- 
fied." From  then  on,  as  he  afterwards  asserted,  the  sub- 
ject haunted  him  ;  hence  the  journal  of  1837. 

It  will  thus  be  seen  that  the  idea  of  the  variability  of 
species  came  to  Charles  Darwin  as  an  inference  from 
personal  observations  in  the  field,  not  as  a  thought  bor- 
rowed from  books.  He  had,  of  course,  read  the  works 
of  his  grandfather  much  earlier  in  life,  but  the  argu- 
ments of  the  Zoonomia  and  Temple  of  Nature  had  not 
served  in  the  least  to  weaken  his  acceptance  of  the  cur- 
rent belief  in  fixity  of  species.  Nor  had  he  been  more 
impressed  with  the  doctrine  of  Lamarck,  so  closely  sim- 
ilar to  that  of  his  grandfather.  Indeed,  even  after  his 
South  American  experience  had  aroused  him  to  a  new 
point  of  view  he  was  still  unable  to  see  anything  of 
value  in  these  earlier  attempts  at  an  explanation  of  the 
variation  of  species.  In  opening  his  journal,  therefore, 
he  had  no  preconceived  notion  of  upholding  the  views  of 
these  or  any  other  makers  of  hypotheses,  nor  at  the 
time  had  he  formulated  any  hypothesis  of  his  own.  His 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

mind  was  open  and  receptive;  be  was  eager  only  for 
facts  which  might  lead  him  to  an  understanding  of  a 


CHARLES  ROBERT  DARWIN 

problem  which  seemed  utterly  obscure.  It  was  some- 
thing to  feel  sure  that  species  have  varied;  but  how 
have  such  variations  been  brought  about  ? 

It  was  not  long  before  Darwin  found  a  cle\v  which  he 
thought  might  lead  to  the  answer  he  sought.  In  cast- 
ing about  for  facts  he  had  soon  discovered  that  the 

304 


THE   CENTURY'S   PROGRESS   IN   BIOLOGY 

most  available  field  for  observation  lay  among  domesti- 
cated animals,  whose  numerous  variations  within  specific 
lines  are  familiar  to  every  one.  Thus  under  domestica- 
tion creatures  so  tangibly  different  as  a  mastiff  and  a 
terrier  have  sprung  from  a  common  stock.  So  have  the 
Shetland  pony,  the  thoroughbred,  and  the  draught- 
horse.  In  short,  there  is  no  domesticated  animal  that 
has  not  developed  varieties  deviating  more  or  less  wide- 
ly from  the  parent  stock.  Now  how  has  this  been  ac- 
complished ?  Why,  clearly,  by  the  preservation,  through 
selective  breeding,  of  seemingly  accidental  variations. 
Thus  one  horseman,  by  constantly  selecting  animals 
that  "chance"  to  have  the  right  build  and  stamina, 
finally  develops  a  race  of  running-horses  ;  while  another 
horseman,  by  selecting  a  different  series  of  progenitors, 
has  developed  a  race  of  slow,  heavy  draught-animals. 

So  far  so  good  ;  the  preservation  of  "  accidental "  va- 
riations through  selective  breeding  is  plainly  a  means  by 
which  races  may  be  developed  that  are  very  different 
from  their  original  parent  form.  But  this  is  under 
man's  supervision  and  direction.  By  what  process  could 
such  selection  be  brought  about  among  creatures  in  a 
state  of  nature?  Here  surely  was  a  puzzle,  and  one  that 
must  be  solved  before  another  step  could  be  taken  in 
this  direction. 

The  key  to  the  solution  of  this  puzzle  came  into  Dar- 
win's mind  through  a  chance  reading  of  the  famous 
essay  on  "  Population  "  which  Thomas  Kobert  Malthus 
had  published  almost  half  a  century  before.  This  essay, 
expositing  ideas  by  no  means  exclusively  original  with 
Malthus,  emphasizes  the  fact  that  organisms  tend  to 
increase  at  a  geometrical  ratio  through  successive  gen- 
erations, and  hence  would  overpopulate  the  earth  if  not 
u  305 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

somehow  kept  in  check.  Cogitating  this  thought,  Dar- 
win gained  a  new  insight  into  the  processes  of  nature. 
He  saw  that  in  virtue  of  this  tendency  of  each  race  of 
beings  to  overpopulate  the  earth,  the  entire  organic 
world,  animal  and  vegetable,  must  be  in  a  state  of 
perpetual  carnage  and  strife,  individual  against  indi- 
vidual, fighting  for  sustenance  and  life. 

That  idea  fully  imagined,  it  becomes  plain  that  a  select- 
ive influence  is  all  the  time  at  work  in  nature,'since  only 
a  few  individuals,  relatively,  of  each  generation  can  come 
to  maturity,  and  these  few  must,  naturally,  be  those 
best  fitted  to  battle  with  the  particular  circumstances 
in  the  midst  of  which  they  are  placed.  In  other  words, 
the  individuals  best  adapted  to  their  surroundings  will, 
on  the  average,  be  those  that  grow  to  maturity  and 
produce  offspring.  To  these  offspring  will  be  trans- 
mitted the  favorable  peculiarities.  Thus  these  pecul- 
iarities will  become  permanent,  and  nature  will  have 
accomplished  precisely  what  the  human  breeder  is  seen 
to  accomplish.  Grant  that  organisms  in  a  state  of 
nature  vary,  however  slightly,  one  from  another  (which 
is  indubitable),  and  that  such  variations  will  be  trans- 
mitted by  a  parent  to  its  offspring  (which  no  one  then 
doubted);  grant,  further,  that  there  is  incessant  strife 
among  the  various  organisms,  so  that  only  a  small  pro- 
portion can  come  to  maturity — grant  these  things,  said 
Darwin,  and  we  have  an  explanation  of  the  preservation 
of  variations  which  leads  on  to  the  transmutation  of 
species  themselves. 

This  wronderful  coign  of  vantage  Darwin  had  reached 
by  J&39.  Here  was  the  full  outline  of  his  theory  ;  here 
were  the  ideas  which  afterwards  came  to  be  embalmed 
in  familiar  speech  in  the  phrases  "  spontaneous  varia- 

306 


T11E   CENTURY'S   PROGRESS    IN    BIOLOGY 

tion,"  and  the  "survival  of  the  fittest,"  through  "nat- 
ural selection."  After  such  a  discovery  any  ordinary 
man  would  at  once  have  run  through  the  streets  of 
science,  so  to  speak,  screaming  "  Eureka  !"  Not  so  Dar- 
win. He  placed  the  manuscript  outline  of  his  theory  in 
his  portfolio,  and  went  on  gathering  facts  bearing  on  his 
discovery.  In  1844  he  made  an  abstract  in  a  manuscript 
book  of  the  mass  of  facts  by  that  time  accumulated. 
He  showed  it  to  his  friend  Hooker,  made  careful  provi- 
sion for  its  publication  in  the  event  of  his  sudden  death, 
then  stored  it  away  in  his  desk,  and  went  ahead  with 
the  gathering  of  more  data.  This  was  the  unexploded 
powder-mine  to  which  I  have  just  referred. 

Twelve  years  more  elapsed;  years  during  which  the 
silent  worker  gathered  a  prodigious  mass  of  facts,  an- 
swered a  multitude  of  objections  that  arose  in  his  own 
mind,  vastly  fortified  his  theory.  All  this  time  the  toiler 
was  an  invalid,  never  knowing  a  day  free  from  illness 
and  discomfort,  obliged  to  husband  his  strength,  never 
able  to  work  more  than  an  hour  and  a  half  at  a  stretch ; 
yet  he  accomplished  what  would  have  been  vast  achieve- 
ments fdr  half  a  dozen  men  of  robust  health.  Two 
friends  among  the  eminent  scientists  of  the  day  knew  of 
his  labors— Sir  Joseph  Hooker,  the  botanist,  and  Sir 
Charles  Lyell,  the  geologist.  Gradually  Hooker  had 
come  to  be  more  than  half  a  convert  to  Darwin's  views. 
Lyell  was  still  sceptical,  yet  he  urged  Darwin  to  publish 
his  theory  without  further  delay,  lest  he  be  forestalled. 
At  last  the  patient  worker  decided  to  comply  with  this 
advice,  and  in  1856  he  set  to  work  to  make  another  and 
fuller  abstract  of  the  mass  of  data  he  had  gathered. 

And  then  a  strange  thing  happened.  After  Darwin 
had  been  at  work  on  his  "abstract"  about  two  years, 

307 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

but  before  he  had  published  a  line  of  it,  there  came  to 
him  one  clay  a  pnper  in  manuscript,  sent  for  his  approval 
by  a  naturalist  friend,  named  Alfred  Russell  Wallace, 
who  had  been  for  some  time  at  work  in  the  East  India 


ALFRED   RUSSELL    WALLACE 


Archipelago.     He   read    the   paper,  and,  to  his  amaze- 
ment, found  that  it  contained  an  outline  of  the  same 


THE   CENTURY'S   PROGRESS   IN   BIOLOGY 

theory  of  "  natural  selection  "  which  he  himself  had 
originated  and  for  twenty  years  had  worked  upon. 
Working  independently,  on  opposite  sides  of  the  globe, 
Darwin  and  Wallace  had  hit  upon  the  same  explanation 
of  the  cause  of  transmutation  of  species.  "  Were  Wal- 
lace's paper  an  abstract  of  my  unpublished  manuscript 
of  1844,"  said  Darwin,  "  it  could  not  better  express  my 
ideas." 

Here  was  a  dilemma.  To  publish  this  paper  with  no 
word  from  Darwin  would  give  Wallace  priority,  and 
wrest  from  Darwin  the  credit  of  a  discovery  which  he 
had  made  years  before  his  co-discoverer  entered  the 
field.  Yet,  on  the  other  hand,  could  Darwin  honorably 
do  otherwise  than  publish  his  friend's  paper  and  himself 
remain  silent?  It  was  a  complication  well  calculated  to 
try  a  man's  soul.  Darwin's  was  equal  to  the  test. 
Keenly  alive  to  the  delicacy  of  the  position,  he  placed 
the  whole  matter  before  his  friends  Hooker  and  Lyell, 
and  left  the  decision  as  t'o  a  course  of  action  absolutely 
to  them.  Needless  to  say,  these  great  men  did  the  one 
thing  which  insured  full  justice  to  all  concerned.  They 
counselled  a  joint  publication,  to  include  on  the  one 
hand  Wallace's  paper,  and  on  the  other  an  abstract  of 
Darwin's  ideas,  in  the  exact  form  in  which  it  had  been 
outlined  by  the  author  in  a  letter  to  Asa  Gray  in  the 
previous  year — an  abstract  which  was  in  Gray's  hands 
before  Wallace's  paper  was  in  existence.  This  joint 
production,  together  with  a  full  statement  of  the  facts 
of  the  case,  was  presented  to  the  Linnasan  Society  of 
London  by  Hooker  and  Lyell  on  the  evening  of  July  1, 
1858,  this  being,  by  an  odd  coincidence,  the  twenty-first 
anniversary  of  the  day  on  which  Darwin  had  opened 
his  journal  to  collect  facts  bearing  on  the  "species  ques- 

309 


THE  STORY  OF  NINETEENTH-CENTURY   SCIENCE 

tion."  Not  often  before  in  the  history  of  science  has  it 
happened  that  a  great  theory  has  been  nurtured  in  its 
author's  brain  through  infancy  and  adolescence  to  its 
full  legal  majority  before  being  sent  out  into  the  world. 
Thus  the  fuse  that  led  to  the  great  po \vder-mine  had 
been  lighted.  The  explosion  itself  came  more  than  a 
year  later,  in  November,  1859,  when  Darwin,  after  thir- 
teen months  of  further  effort,  completed  the  outline  of 
his  theory,  which  was  at  first  begun  as  an  abstract  for 
the  Linnaean  Society,  but  which  grew  to  the  size  of  an 
independent  volume  despite  his  efforts  at  condensation, 
and  which  was  given  that  ever-to-be-famous  title,  The 
Origin  of  Species  by  means  of  Natural  Selection,  or  the 
Preservation  of  Favored  Races  in  the  Struggle  for  Life. 
And  what  an  explosion  it  was !  The  joint  paper  of  1858 
had  made  a  momentary  flare,  causing  the  hearers,  as 
Hooker  said,  to  "  speak  of  it  with  bated  breath,"  but  be- 
yond that  it  made  no  sensation.  What  the  result  was 
when  the  Origin  itself  appeared,  no  one  of  our  genera- 
tion need  be  told.  The  rumble  and  roar  that  it  made  in 
the  intellectual  world  have  not  yet  altogether  ceased  to 
echo  after  forty  years  of  reverberation. 


v 

To  the  Origin  of  Species,  then,  and  to  its  author, 
Charles  Darwin,  must  always  be  ascribed  chief  credit 
for  that  vast  revolution  in  the  fundamental  beliefs  of 
our  race  which  has  come  about  since  1859,  and  made 
the  second  half  of  the  century  memorable.  But  it  must 
not  be  overlooked  that  no  such  sudden  metamorphosis 
could  have  been  effected  had  it  not  been  for  the  aid  of  a 
few  notable  lieutenants,  who  rallied  to  the  standards  of 

310 


THOMAS  HENRY  HUXLEY 

From  a  photograph  by  W.  and  D.  Downey,  London 


TIIE   CENTURY'S   PROGRESS   IN  BIOLOGY 

the  leader  immediately  after  the  publication  of  the  Ori- 
gin. Darwin  had  all  along  felt  the  utmost  confidence 
in  the  ultimate  triumph  of  his  ideas.  "Our  posterity," 
he  declared  in  a  letter  to  Hooker,  "  will  marvel  as  much 
about  the  current  belief  [in  special  creation]  as  we  do 
about  fossil  shells  having  been  thought  to  be  created  as 
we  now  see  them."  But  he  fully  realized  that  for  the 
present  success  of  his  theory  of  transmutation  the  cham- 
pionship of  a  few  leaders  of  science  was  all-essential. 
He  felt  that  if  he  could  make  converts  of  Hooker  and 
Lyell  and  of  Thomas  Henry  Huxley  at  once,  all  would 
be  well. 

His  success  in  this  regard,  as  in  others,  exceeded  his 
expectations.  Hooker  was  an  ardent  disciple  from  read- 
ing the  proof-sheets  before  the  book  was  published ; 
Lyell  renounced  his  former  beliefs  and  fell  into  line  a 
few  months  later ;  while  Huxley,  so  soon  as  he  had  mas- 
tered the  central  idea  of  natural  selection,  marvelled 
that  so  simple  yet  all-potent  a  thought  had  escaped  him 
so  long,  and  then  rushed  eagerly  into  the  fray,  wielding 
the  keenest  dialectic  blade  that  was  drawn  during  the 
entire  controversy.  Then,  too,  unexpected  recruits  were 
found  in  Sir  John  Lubbock  and  John  Tyndall,  who  car- 
ried the  war  eagerly  into  their  respective  territories; 
while  Herbert  Spencer,  who  had  advocated  a  doctrine 
of  transmutation  on  philosophic  grounds  some  years  be- 
fore Darwin  published  the  key  to  the  mystery — and  who 
himself  had  barely  escaped  independent  discovery  of 
that  key — lent  his  masterful  influence  to  the  cause.  In 
America,  the  famous  botanist  Asa  Gray,  who  had  long 
been  a  correspondent  of  Darwin's,  but  whose  advocacy 
of  the  new  theory  had  not  been  anticipated,  became  an 
ardent  propagandist;  while  in  Germany  Ernst  Heinrich 

313 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

Haeckel,  the  youthful  but  already  noted  zoologist,  took 
up  the  fight  with  equal  enthusiasm. 


ASA  GRAY 


Against  these  few  doughty  champions — with  here  and 
there  another  of  less  general  renown — was  arrayed,  at 
the  outset,  practically  all  Christendom.  The  interest  of 
the  question  came  home  to  every  person  of  intelligence, 
whatever  his  calling,  and  the  more  deeply  as  it  became 
more  and  more  clear,  how  far-reaching  are  the  real  bear- 

314 


THE   CENTURY'S   PROGRESS   IN   BIOLOGY 

ings  of  the  doctrine  of  natural  selection.  Soon  it  was 
seen  that  should  the  doctrine  of  the  survival  of  the 
favored  races  through  the  struggle  for  existence  win, 
there  must  come  with  it  as  radical  a  change  in  man's 
estimate  of  his  own  position  as  had  corne  in  the  day 
when,  through  the  efforts  of  Copernicus  and  Galileo,  the 
world  was  dethroned  from  its  su^^sed  central  position 
in  the  universe.  The  whole  cH^vative  majority  of 
mankind  recoiled  from  this  necessity  with  horror.  And 
this  conservative  majority  included  not  laymen  merely, 
but  a  vast  preponderance  of  the  leaders  of  science  also. 

With  the  open-minded  minority,  on  the  other  hand, 
the  theory  of  natural  selection  made  its  way  by  leaps 
and  bounds.  Its  delightful  simplicity — which  at  first 
sight  made  it  seem  neither  new  nor  important — coupled 
with  the  marvellous  comprehensiveness  of  its  implica- 
tions, gave  it  a  hold  on  the  imagination,  and  secured  it 
a  hearing  where  other  theories  of  transmutation  of  spe- 
cies had  been  utterly  scorned.  Men  who  had  found 
Lamarck's  conception  of  change  through  voluntary  ef- 
fort ridiculous,  and  the  vaporings  of  the  Vestiges  alto- 
gether despicable,  men  whose  scientific  cautions  held 
them  back  from  Spencer's  deductive  argument,  took 
eager  hold  of  that  tangible,  ever-present  principle  of 
natural  selection,  and  were  led  on  and  on  to  its  goal. 
Hour  by  hour  the  attitude  of  the  thinking  world  tow- 
ards this  new  principle  changed  ;  never  before  was  so 
great  a  revolution  wrought  so  suddenly. 

Nor  was  this  merely  because  "  the  times  were  ripe  " 
or  "men's | minds  prepared  for  evolution."  Darwin 
himself  bears  witness  that  this  was  not  altogether  so. 
All  through  the  years  in  which  he  brooded  this  theory 
he  sounded  his  scientific  friends,  and  could  find  among 

815 


THE   STORY  OF  NINETEENTH-CENT IJ1IY  SCIENCE 

them  not  one  who  acknowledged  a  doctrine  of  transmu- 
tation. The  reaction  from  the  standpoint  of  Lamarck 
and  Erasmus  Darwin  and  Goethe  had  been  complete, 
and  when  Charles  Darwin  avowed  his  own  conviction 
he  expected  always  to  have  it  met  with  ridicule  or 
contempt.  In  1857  there  was  but  one  man  speaking 
with  any  large  degree  of  authority  in  the  world  who 
openly  avowed  a  belief  in  transmutation  of  species— that 
man  being  Herbert  Spencer.  But  the  Origin  of  Species 
came,  as  Huxley  has  said,  like  a  flash  in  the  darkness,  en- 
abling the  benighted  voyager  to  see  the  way.  The  score 
of  years  during  which  its  author  had  waited  and  worked 
had  been  years  well  spent.  Darwin  had  become,  as  he 
himself  says,  a  veritable  Croesus,  "  overwhelmed  with 
his  riches  in  facts  " — facts  of  zoology,  of  selective  artifi- 
cial breeding,  of  geographical  distribution  of  animals,  of 
embryology,  of  paleontology.  He  had  massed  his  facts 
about  his  theory,  condensed  them  and  recondensed,  un- 
til his  volume  of  five  hundred  pages  was  an  encyclo- 
paedia in  scope.  During  those  long  years  of  musing  he 
had  thought  out  almost  every  conceivable  objection  to 
his  theory,  and  in  his  book  every  such  objection  was 
stated  with  fullest  force  and  candor,  together  with  such 
reply  as  the  facts  at  command  might  dictate.  It  was 
the  force  of  those  twenty  years  of  effort  of  a  master 
mind  that  made  the  sudden  breach  in  the  breastwork  of 
current  thought. 

Once  this  breach  was  effected,  the  work  of  conquest 
went  rapidly  on.  Day  by  day  squads  of  the  enemy 
capitulated  and  struck  their  arms.  By  the  time  another 
score  of  years  had  passed  the  doctrine  of  evolution  had 
become  the  working  hypothesis  of  the  scientific  world, 
The  revolution  had  been  effected. 

316 


THE   CENTURY'S   PROGRESS   IN   BIOLOGY 

And  from  amid  the  wreckage  of  opinion  and  belief 
stands  forth  the  figure  of  Charles  Darwin,  calm,  imper- 
turbable, serene;  scatheless  to  ridicule,  contumely,  abuse ; 
unspoiled  by  ultimate  success  ;  unsullied  alike  by  the 
strife  and  the  victory — take  him  for  all  in  all,  for  char- 
acter, for  intellect,  for  what  he  was  and  what  he  did, 
perhaps  the  most  Soc rat ic  figure  of  the  century.  When, 
in  1882,  he  died,  friend  and  foe  alike  conceded  that  one  of 
the  greatest  sons  of  men  had  rested  from  his  labors,  and 
all  the  world  felt  it  fitting  that  the  remains  of  Charles 
Darwin  should  be  entombed  in  Westminster  Abbey, 
close  beside  the  honored  grave  of  Isaac  Newton.  Nor 
were  there  many  who  would  dispute  the  justice  of  Hux- 
ley's estimate  of  his  accomplishment :  "  He  found  a  great 
truth  trodden  under  foot.  Keviled  by  bigots,  and  ridiculed 
by  all  the  world,  he  lived  long  enough  to  see  it,  chiefly  by 
his  own  efforts,  irrefragably  established  in  science,  in- 
separably incorporated  with  the  common  thoughts  of  men, 
and  only  hated  and  feared  by  those  who  would  revile,  but 
dare  not." 

VI 

Wide  as  are  the  implications  of  the  great  truth  which 
Darwin  and  his  co-workers  established,  however,  it 
leaves  quite  untouched  the  problem  of  the  origin  of 
those  "favored  variations"  upon  which  it  operates. 
That  such  variations  are  due  to  fixed  and  determinate 
causes  no  one  understood  better  than  Darwin  ;  but  in 
his  original  exposition  of  his  doctrine  he  made  no  as- 
sumption as  to  what  these  causes  are.  He  accepted  the 
observed  fact  of  variation — as  constantly  witnessed,  for 
example,  in  the  differences  between  parents  and  off- 
spring—and went  ahead  from  this  assumption. 

317 


THE  STORY   OF   NINETEENTH-CENTURY   SCIENCE 

But  as  soon  as  the  validity  of  the  principle  of  natural 
selection  came  to  be  acknowledged,  speculators  began  to 
search  for  the  explanation  of  those  variations  which,  for 
purposes  of  argument,  had  been  provisionally  called 
"  spontaneous."  Herbert  Spencer  had  all  along  dwelt 
on  this  phase  of  the  subject,  expounding  the  Lamarck- 
ian  conceptions  of  the  direct  influence  of  the  environ- 
ment (an  idea  which  had  especially  appealed  to  Buffon 
and  to  Geoffroy  Saint-Hilaire),  and  of  effort  in  response 
to  environment  and  stimulus  as  modifjang  the  individu- 
al organism,  and  thus  supplying  the  basis  for  the  opera- 
tion of  natural  selection.  Haeckel  also  became  an  advo- 
cate of  this  idea,  and  presently  there  arose  a  so-called 
school  of  neo-Lamarckians,  which  developed  particular 
strength  and  prominence  in  America,  under  the  leader- 
ship of  Professors  A.  Hyatt  and  E.  D.  Cope. 

But  just  as  the  tide  of  opinion  was  turning  strongly  in 
this  direction,  an  utterly  unexpected  obstacle  appeared 
in  the  form  of  the  theory  of  Professor  August  Weis- 
mann,  put  forward  in  1883,  which  antagonized  the  La- 
marckian  conception  (though  not  touching  the  Darwin- 
ian, of  which  Weismann  is  a  firm  upholder)  by  denying 
that  individual  variations,  however  acquired  by  the  ma- 
ture organism,  are  transmissible.  The  flurry  which  this 
denial  created  has  not  yet  altogether  subsided,  but  sub- 
sequent observations  seem  to  show  that  it  was  quite  dis- 
proportionate to  the  real  merits  of  the  case.  Notwith- 
standing Professor  Weismann's  objections,  the  balance 
of  evidence  appears  to  favor  the  view  that  the  Lamarck- 
ian  factor  of  acquired  variations  stands  as  the  comple- 
ment of  the  Darwinian  factor  of  natural  selection  in  ef- 
fecting the  transmutation  of  species. 

Even  though  this  partial  explanation  of  what  Pro- 

318 


THE   CENTURY'S   PROGRESS   IN   BIOLOGY 

fessor  Cope  calls  the  "  origin  of  the  fittest "  be  accepted, 
there  still  remains  one  great  life  problem  which  the  doc- 
trine of  evolution  does  not  touch.  The  origin  of  species, 
genera,  orders,  and  classes  of  beings  through  endless 
transmutations  is  in  a  sense  explained  ;  but  what  of  the 
first  term  of  this  long  series?  Whence  came  that  pri- 
mordial organism  whose  transmuted  descendants  make 
up  the  existing  faunas  and  floras  of  the  globe  ? 


ERNEST   HAECKEL 


There  was  a  time,  soon  after  the  doctrine  of  evolution 
gained  a  hearing,  when  the  answer  to  that  question 
seemed  to  some  scientists  of  authority  to  have  been 

319 


THE   STORY   OF   NINETEENTH-CENTURY    SCIENCE 

given  by  experiment.  Eecurring  to  a  former  belief,  and 
repeating  some  earlier  experiments,  the  director  of  the 
Museum  of  Natural  History  at  Eouen,  M.  F.  A.  Pouchet, 
reached  the  conclusion  that  organic  beings  are  sponta- 
neously generated  about  us  constantly,  in  the  familiar 
processes  of  putrefaction,  which  were  known  to  be  due 
to  the  agency  of  microscopic  bacteria.  But  in  1862 
Louis  Pasteur  proved  that  this  seeming  spontaneous 
generation  is  in  reality  due  to  the  existence  of  germs  in 
the  air.  Notwithstanding  the  conclusiveness  of  these 
experiments,  the  claims  of  Pouchet  were  revived  in  Eng- 
land ten  years  later  by  Professor  Bastian  ;  but  then  the 
experiments  of  John  Tyndall,  fully  corroborating  the 
results  of  Pasteur,  gave  a  final  quietus  to  the  claim  of 
"spontaneous  generation"  as  hitherto  formulated. 

There  for  the  moment  the  matter  rests.  But  the  end 
is  not  yet.  Fauna  and  flora  are  here,  and,  thanks  to 
Lamarck  and  Wallace  and  Darwin,  their  development, 
through  the  operation  of  those  "secondary  causes" 
which  we  call  laws  of  nature,  has  been  proximally  ex- 
plained. The  lowest  forms  of  life  have  been  linked  with 
the  highest  in  unbroken  chains  of  descent.  Meantime, 
through  the  efforts  of  chemists  and  biologists,  the  gap 
between  the  inorganic  and  the  organic  worlds,  which 
once  seemed  almost  infinite,  has  been  constantly  nar- 
rowed. Already  philosophy  can  throw  a  bridge  across 
that  gap.  But  inductive  science,  which  builds  its  own 
bridges,  has  not  yet  spanned  the  chasm,  small  though  it 
appear.  Until  it  shall  have  done  so,  the  bridge  of  or- 
ganic evolution  is  not  quite  complete :  yet  even  as  it 
stands  to-day  it  is  the  most  stupendous  scientific  struct- 
ure of  our  century. 

320 


CHAPTER  X 

THE   CENTURY'S   PROGRESS   IN   ANATOMY   AND 
PHYSIOLOGY 


THE  focal  points  of  the  physiological  world  towards 
the  close  of  the  eighteenth  century  were  Italy  and  Eng- 
land, but  when  Spallanzani  and  Hunter  passed  away  the 
scene  shifted  to  France.  The  time  was  peculiarly  pro- 
pitious, as  the  recent  advances  in  many  lines  of  science 
had  brought  fresh  data  for  the  student  of  animal  life 
which  were  in  need  of  classification,  and,  as  several 
minds  capable  of  such  a  task  were  in  the  field,  it  was 
natural  that  great  generalizations  should  have  come  to 
be  quite  the  fashion.  Thus  it  \yas  that  Cuvier  came  for- 
ward with  a  brand-new  classification  of  the  animal  king- 
dom, establishing  four  great  types  of  being,  which  he 
called  vertebrates,  molluscs,  articulates,  and  radiates. 
Lamarck  had  shortly  before  established  the  broad  dis- 
tinction between  animals  with  and  those  without  a  back- 
bone; Cuvier's  classification  divided  the  latter — the  in- 
vertebrates— into  three  minor  groups.  And  this  divis- 
ion, familiar  ever  since  to  all  students  of  zoology,  has 
only  in  very  recent  years  been  supplanted,  and  then  not 
by  revolution,  but  by  a  further  division,  which  the  elab- 
orate recent  studies  of  lower  forms  of  life  seemed  to 
make  desirable. 

,x  321 


THE   STORY   OF  NINETEENTH-CENTURY   SCIENCE 

In  the  course  of  those  studies  of  comparative  anato- 
my which  led  to  his  new  classification,  Cuvier's  atten- 
tion was  called  constantly  to  the  peculiar  co-ordination 
of  parts  in  each  individual  organism.  Thus  an  animal 
with  sharp  talons  for  catching  living  prey — as  a  member 
of  the  cat  tribe — has  also  sharp  teeth,  adapted  for  tear- 
ing up  the  flesh  of  its  victim,  and  a  particular  type  of 
stomach,  quite  different  from  that  of  herbivorous  creat- 
ures. This  adaptation  of  all  the  parts  of  the  animal  to 
one  another  extends  to  the  most  diverse  parts  of  the  or- 
ganism, and  enables  the  skilled  anatomist,  from  the  ob- 
servation of  a  single  typical  part,  to  draw  inferences  as 
to  the  structure  of  the  entire  animal — a  fact  which  was 
of  vast  aid  to  Cuvier  in  his  studies  of  paleontology.  It 
did  not  enable  Cuvier,  nor  does  it  enable  any  one  else, 
to  reconstruct  fully  the  extinct  animal  from  observation 
of  a  single  bone,  as  has  sometimes  been  asserted,  but 
what  it  really  does  establish,  in  the  hands  of  an  expert, 
is  sufficiently  astonishing. 

Of  course  this  entire  principle,  in  its  broad  outlines,  is 
something  with  which  every  student  of  anatomy  had 
been  familiar  from  the  time  when  anatomy  was  first 
studied,  but  the  full  expression  of  the  "  law  of  co-ordina- 
tion," as  Cuvier  called  it,  had  never  been  explicitly  made 
before;  and  notwithstanding  its  seeming  obviousness,  the 
exposition  which  Cuvier  made  of  it  in  the  introduction 
to  his  classical  work  on  comparative  anatomy,  which 
was  published  during  the  first  decade  of  the  century, 
ranks  as  a  great  discovery.  It  is  one  of  those  general- 
izations which  serve  as  guide-posts  to  other  discover- 
ries. 

Much  the  same  thing  may  be  said  of  another  general- 
ization regarding  the  animal  body,  which  the  brilliant 

_  322 


PROGRESS   IN   ANATOMY   AND   PHYSIOLOGY 

young  French  physician  Marie  Francois  Bichat  made  in 
calling  attention  to  the  fact  that  each  vertebrate  organ- 
ism, including  man,  has  really  two  quite  different  sets  of 


MARTE   FRANgOIS   XAVIER   BICHAT 

From  a  medallion  by  David  d1  Angers 

organs — one  set  under  volitional  control,  and  serving  the 
end  of  locomotion,  the  other  removed  from  volitional 
control,  and  serving  the  ends  of  the  "  vital  processes"  of 
digestion,  assimilation,  and  the  like.  He  called  these' 
sets  of  organs  the  animal  system  and  the  organic  sys- 
tem, respectively.  The  division  thus  pointed  out  was 
not  quite  new,  for  Grimaud,  professor  of  physiology  in 
the  university  of  Montpellier,  had  earlier  made  what 
was  substantially  the  same  classification  of  the  functions 
into  "  internal  or  digestive  and  external  or  locomotive  "; 

323 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

but  it  was  Bichat's  exposition  that  gave  currency  to  the 
idea. 

Far  more  important,  however,  was  another  classifica- 
tion which  Bichat  put  forward  in  his  work  on  anatomy, 
published  just  at  the  beginning  of  the  century.  This  was 
the  division  of  all  animal  structures  into  what  Bichat 
called  tissues,  and  the  pointing  out  that  there  are  really 
only  a  few  kinds  of  these  in  the  body,  making  up  all 
the  diverse  organs.  Thus  muscular  organs  form  one 
system;  membranous  organs  another;  glandular  organs 
a  third ;  the  vascular  mechanism  a  fourth,  and  so  on. 
The  distinction  is  so  obvious  that  it  seems  rather  diffi- 
cult to  conceive  that  it  could  have  been  overlooked  by 
the  earliest  anatomists  ;  but,  in  point  of  fact,  it  is  only 
obvious  because  now  it  has  been  familiarly  taught  for 
almost  a  century.  It  had  never  been  given  explicit  ex- 
pression before  the  time  of  Bichat,  though  it  is  said  that 
Bichat  himself  was  somewhat  indebted  for  it  to  his  mas- 
ter, the  famous  alienist,  Pinel. 

Howeverthat  may  be,  it  is  certain  that  all  subsequent 
anatomists  have  found  Bichat's  classification  of  the  tis- 
sues of  the  utmost  value  in  their  studies  of  the  animal 
functions.  Subsequent  advances  were  to  show  that  the 
distinction  between  the  various  tissues  is  not  really  so 
fundamental  as  Bichat  supposed,  but  that  takes  nothing 
from  the  practical  value  of  the  famous  classification. 


ii 

At  the  same  time  when  these  broad  microscopical  dis- 
tinctions were  being  drawn  there  were  other  workers 
who  were  striving  to  go  even  deeper  into  the  intricacies 
of  the  animal  mechanism  with  the  aid  of  the  microscope. 

324 


PROGRESS   IN   ANATOMY   AND   PHYSIOLOGY 

This  undertaking,  however,  was  beset  with  very  great 
optical  difficulties,  and  for  a  long  time  little  advance 
was  made  upon  the  work  of  preceding  generations. 
Two  great  optical  barriers,  known  technically  as  spher- 
ical and  chromatic  aberration — the  one  -due  to  a  failure 
of  the  rays  of  light  to  fall  all  in  one  plane  when  focalized 
through  a  lens,  the  other  due  to  the  dispersive  action  of 
the  lens  in  breaking  the  white  light  into  prismatic  col- 
ors— confronted  the  makers  of  microscopic  lenses,  and 
seemed  all  but  insuperable.  The  making  of  achromatic 
lenses  for  telescopes  had  been  accomplished,  it  is  true, 
by  Dolland  in  the  previous  century,  by  the  union  of 
lenses  of  crown  glass  with  those  of  flint  glass,  these  two 
materials  having  different  indices  of  refraction  and  dis- 
persion. But,  aside  from  the  mechanical  difficulties 
which  arise  when  the  lens  is  of  the  minute  dimensions 
required  for  use  with  the  microscope,  other  perplexities 
are  introduced  by  the  fact  that  the  use  of  a  wide  pencil 
of  light  is  a  desideratum,  in  order  to  gain  sufficient  illu- 
mination when  large  magnification  is  to  be  secured. 

In  the  attempt  to  overcome  these  difficulties,  the  fore- 
most physical  philosophers  of  the  time  came  to  the  aid 
of  the  best  opticians.  Yery  early  in  the  century,  Dr. 
(afterwards  Sir  David)  Brewster,  the  renowned  Scotch 
physicist,  suggested  that  certain  advantages  might  ac- 
crue from  the  use  of  such  gems  as  have  high  refractive 
and  low  dispersive  indices,  in  place  of  lenses  made  of 
glass.  Accordingly  lenses  were  made  of  diamond,  of 
sapphire,  and  so  on,  and  with  some  measure  of  success. 
But  in  1812  a  much  more  important  innovation  was  intro- 
duced by  Dr.  William  Hyde  Wollaston,  one  of  the  great- 
est and  most  versatile,  and  since  the  death  of  Cavendish 
by  far  the  most  eccentric,  of  English  natural  philosophers. 

325 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

This  was  the  suggestion  to  use  two  plano-convex  lenses, 
placed  at  a  prescribed  distance  apart,  in  lieu  of  the  sin- 
gle double  convex  lens  generally  used.  This  combina- 
tion largely  overcame  the  spherical  aberration,  and  it 
gained  immediate  fame  as  the  "  Wollaston  doublet." 

To  obviate  loss  of  light 
in  such  a  doublet  from  in- 
crease of  reflecting  surfaces, 
Dr.  Brewster  suggested  fill- 
ing the  interspace  between 
the  two  lenses  with  a  ce- 
ment having  the  same  index 
of  refraction  as  the  lenses 
themselves  —  an  improve- 
ment ot  manifest  advan- 
tage. An  improvement  yet 
more  important  was  made 
by  Dr.  Wollaston  himself, 
in  the  introduction  of  the 
WILLIAM  HYDE  WOLLASTON  diaphragm  to  limit  the  field 

of  vision  between  the  lenses, 

instead  of  in  front  of  the  anterior  lens.  A  pair  of  lenses 
thus  equipped,  Dr.  Wollaston  called  the  periscopic  micro- 
scope. Dr.  Brewster  suggested  that  in  such  a  lens  the 
same  object  might  be  attained  with  greater  ease  by  grind- 
ing an  equatorial  groove  about  a  thick  or  globular  lens 
and  filling  the  groove  with  an  opaque  cement.  This  ar- 
rangement found  much  favor,  and  came  subsequently  to 
be  known  as  a  Coddington  lens,  though  Mr.  Coddington 
laid  no  claim  to  being  its  inventor. 

Sir  John  Herschel,  another  of  the  very  great  physicists 
of  the  time,  also  gave  attention  to  the  problem  of  im- 
proving the  microscope,  and  in  1821  he  introduced  what 

326 


PROGRESS   IN   ANATOMY   AND   PHYSIOLOGY 

was  called  an  aplanatic  combination  of  lenses,  in  which, 
as  the  name  implies,  the  spherical  aberration  was  largely 
done  away  with.  It  was  thought  that  the  use  of  this 
Herschel  aplanatic  combination  as  an  eye  -  piece,  com- 
bined with  the  Wollaston  doublet  for  the  objective,  came 
as  near  perfection  as  the  compound  microscope  was  like- 
ly soon  to  come.  But  in  reality  the  instrument  thus 
constructed,  though  doubtless  superior  to  any  predeces- 
sor, was  so  defective  that  for  practical  purposes  the  sim- 
ple* microscope,  such  as  the  doublet  or  the  Coddington, 
was  preferable  to  the  more  complicated  one. 

Many  opticians,  indeed,  quite  despaired  of  ever  being 
able  to  make  a  satisfactory  refracting  compound  micro- 
scope, and  some  of  them  had  taken  up  anew  Sir  Isaac 
Newton's  suggestion  in  reference  to  a  reflecting  micro- 
scope. In  particular,  Professor  Giovanni  Battista  Amici, 
a  very  famous  mathematician  and  practical  optician  of 
Modena,  succeeded  in  constructing  a  reflecting  micro- 
scope which  was  said  to  be  superior  to  any  compound 
microscope  of  the  time,  though  the  events  of  the  ensu- 
ing years  were  destined  to  rob  it  of  all  but  historical 
value.  For  there  were  others,  fortunately,  who  did  not 
despair  of  the  possibilities  of  the  refracting  microscope, 
and  their  efforts  were  destined  before  long  to  be  crowned 
with  a  degree  of  success  not  even  dreamed  of  by  any 
preceding  generation. 

The  man  to  whom  chief  credit  is  due  for  directing 
those  final  steps  that  made  the  compound  microscope  a 
practical  implement  instead  of  a  scientific  toy  was  the 
English  amateur  optician  Joseph  Jackson  Lister.  Com- 
bining mathematical  knowledge  with  mechanical  ingenu- 
ity, and  having  the  practical  aid  of  the  celebrated  opti- 
cian Tulley,  he  devised  formulae  for  the  combination 

327 


THE   STORY   OF   NINETEENTH-CENTURY  SCIENCE 

of  lenses  of  crown  glass  with  others  of  flint  glass,  so 
adjusted  that  the  refractive  errors  of  one  were  corrected 
or  compensated  by  the  other,  with  the  result  of  produc- 
ing lenses  of  hitherto  unequalled  powers  of  definition; 
lenses  capable  of  showing  an  image  highly  magnified, 
yet  relatively  free  from  those  distortions  and  fringes  of 
color  that  had  heretofore  been  so  disastrous  to  true  in- 
terpretation of  magnified  structures. 

Lister  had  begun  his  studies  of  the  lens  in  182±, 
but  it  was  not  until  1830  that  he  contributed  to  the 
Royal  Society  the  famous  paper  detailing  his  theories 
and  experiments.  Soon  after  this  various  Continental 
opticians  who  had  long  been  working  along  similar  lines 
took  the  matter  up,  and  their  expositions,  in  particular 
that  of  Amici,  introduced  the  improved  compound  mi- 
croscope to  the  attention  of  microscopists  everywhere. 
And  it  required  but  the  most  casual  trial  to  convince 
the  experienced  observers  that  a  new  implement  of  sci- 
entific research  had  been  placed  in  their  hands  which 
carried  them  a  long  step  nearer  the  observation  of  the 
intimate  physical  processes  which  lie  at  the  foundation 
of  vital  phenomena.  For  the  physiologist,  this  perfec- 
tion of  the  compound  microscope  had  the  same  signifi- 
cance that  the  discovery  of  America  had  for  the  fifteenth- 
century  geographers  —  it  promised  a  veritable  world  of 
utterly  novel  revelations.  Nor  was  the  fulfilment  of 
that  promise  long  delayed. 


in 

Indeed,  so  numerous  and  so  important  were  the  dis- 
coveries now  made  in  the  realm  of  minute  anatomy  that 
the  rise  of  histology  to  the  rank  of  an  independent  sci- 

328 


PROGRESS   IN   ANATOMY   AND  PHYSIOLOGY 

ence  may  be  said  to  date  from  this  period.  Hitherto, 
ever  since  the  discovery  of  magnify  ing -glasses,  there 
had  been  here  and  there  a  man,  such  as  Leuwenhoek  or 
Malpighi,  gifted  with  exceptional  vision,  and  perhaps 
unusually  happy  in  his  conjectures,  who  made  important 
contributions  to  the  knowledge  of  the  minute  structure 
of  organic  tissues ;  but  now  of  a  sudden  it  became  pos- 
sible for  the  veriest  tyro  to  confirm  or  refute  the  la- 
borious observations  of  these  pioneers,  while  the  skilled 
observer  could  step  easily  beyond  the  barriers  of  vision 
hitherto  quite  impassable.  And  so,' naturally  enough, 
the  physiologists  of  the  fourth  decade  of  our  century 
rushed  as  eagerly  into  the  new  realm  of  the  microscope 
as,  for  example,  their  successors  of  to-day  are  exploring 
the  realm  of  the  X  ray. 

Lister  himself,  who  had  become  an  eager  interrogator 
of  the  instrument  he  had  perfected,  made  many  impor- 
tant discoveries,  the  most  notable  being  his  final  set- 
tlement of  the  long -mooted  question  as  to  the  true 
form  of  the  red  corpuscles  of  the  human  blood.  In 
reality,  as  everybody  knows  nowadays,  these  are  bicon- 
cave disks,  but  owing  to  their  peculiar  figure  it  is  easily 
possible  to  misinterpret  the  appearances  they  present 
when  seen  through  a  poor  lens,  and  though  Dr.  Thomas 
Young  and  various  other  observers  had  come  very  near 
the  truth  regarding  them,  unanimity  of  opinion  was  pos- 
sible only  after  the  verdict  of  the  perfected  microscope 
was  given. 

These  blood  corpuscles  are  so  infinitesimal  in  size  that 
something  like  five  millions  of  them  are  found  in  each 
cubic  millimetre  of  the  blood,  yet  they  are  isolated  par- 
ticles, each  having,  so  to  speak,  its  own  personality. 
This,  of  course,  had  been  known  to  microscopists  since 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

the  days  of  the  earliest  lenses.  It  had  been  noticed, 
too,  by  here  and  there  an  observer,  that  certain  of  the 
solid  tissues  seemed  to  present  something  of  a  granular 
texture,  as  if  they  too,  in  their  ultimate  constitution, 
were  made  up  of  particles.  And  now,  as  better  and  bet- 
ter lenses  were  constructed,  this  idea  gained  ground 
constantly,  though  for  a  time  no  one  sa\v  its  full  signif- 
icance. In  the  case  of  vegetable  tissues,  indeed,  the  fact 
that  little  particles  encased  in  a  membranous  covering, 
and  called  cells,  are  the  ultimate  visible  units  of  struct- 
ure had  long  been  known. 
But  it  was  supposed  that 
animal  tissues  differed  radi- 
cally from  this  construction. 
The  elementary  particles  of 
vegetables  "  were  regarded 
to  a  certain  extent  as  indi- 
viduals which  composed  the 
entire  plant,  while,  on  the 
other  hand,  no  such  view 
was  taken  of  the  elementary 
parts  of  animals." 

In  the  year  1833  a  further 
insight  into  the  nature  of  the 
ultimate  particles  of  plants 
was  gained  through  the  ob- 
servation of  the  English  microscopist  Robert  Brown, 
who,  in  the  course  of  his  microscopic  studies  of  the  epi- 
dermis of  orchids,  discovered  in  the  cells  "an  opaque 
spot,"  which  he  named  the  nucleus.  Doubtless  the  same 
"  spot "  had  been  seen  often  enough  before  by  other  ob- 
servers, but  Brown  was  the  first  to  recognize  it  as  a 
component  part  of  the  vegetable  cell,  and  to  give  it 

330 


MATTHIAS  JAKOB  SCHLEIDEX 


PROGRESS   IN   ANATOMY    AND   PHYSIOLOGY 

a  name.  That  this  newly  recognized  structure  must  be 
important  in  the  economy  of  the  cell  was  recognized  by 
Brown  himself,  and  by  the  celebrated  German  Meyen, 
who  dealt  with  it  in  his  work  on  vegetable  physiology, 
published  not  long  afterwards ;  but  it  remained  for  an- 
other German,  the  professor  of  botany  in  the  university 
of  Jena,  Dr.  M.  J.  Schleiden,  to  bring  the  nucleus  to 
popular  attention,  and  to  assert  its  all-importance  in  the 
economy  of  the  cell. 

Schleiden  freely  acknowledged  his  indebtedness  to 
Brown  for  first  knowledge  of  the  nucleus,  but  he  soon 
carried  his  studies  of  that  structure  far  beyond  those  of 
its  discoverer.  He  came  to  believe  that  the  nucleus  is 
really  the  most  important  portion  of  the  cell,  in  that  it 
is  the  original  structure  from  which  the  remainder  of 
the  cell  is  developed.  Hence  he  named  it  the  cytoblast. 
He  outlined  his  views  in  an  epochal  paper  published  in 
Miiller's  Archives  in  1838,  under  title  of  "  Beitrage  zur 
Pbytogenesis."  This  paper  is  in  itself  of  value,  yet  the 
most  important  outgrowth  of  Schleiden's  observations  of 
the  nucleus  did  not  spring  from  his  own  labors,  bat  from 
those  of  a  friend  to  whom  he  mentioned  his  discoveries 
the  year  previous  to  their  publication.  This  friend  was 
Dr.  Theoclor  Schwann,  professor  of  physiology  in  the 
university  of  Louvain. 

At  the  moment  when  these  observations  were  com- 
municated to  him  Schwann  was  puzzling  over  certain 
details  of  animal  histology  which  he  could  not  clearly 
explain.  His  great  teacher,  Johannes  Miiller,  had  called 
attention  to  the  strange  resemblance  to  vegetable  cells 
shown  by  certain  cells  of  the  chorda  dorsalis  (the  em- 
bryonic cord  from  which  the  spinal  column  is  devel- 
oped), and  Schwann  himself  had  discovered  a  corre- 

331 


THE   STORY    OF   NINETEENTH-CENTURY   SCIENCE 

spending  similarity  in  the  branchial  cartilage  of  a  tad- 
pole. Then,  too,  the  researches  of  Friedricli  Henle  had 
shown  that  the  particles  that  make  up  the  epidermis  of 
animals  are  very  cell-like  in  appearance.  Indeed,  the 
cell-like  character  of  certain  animal  tissues  had  come  to 
be  matter  of  common  note  among  students  of  minute 
anatomy.  Schwann  felt  that  this  similarity  could  not 
be  mere  coincidence,  but  he  had  gained  no  clew  to 
further  insight  until  Schleiden  called  his  attention  to 
the  nucleus.  Then  at  once  he  reasoned  that  if  there 
really  is  the  correspondence  between  vegetable  and  ani- 
mal tissues  that  he  suspected,  and  if  the  nucleus  is  so  im- 
portant in  the  vegetable  cell  as  Schleiden  believed,  the 
nucleus  should  also  be  found  in  the  ultimate  particles  of 
animal  tissues. 

Schwann's  researches  soon  showed  the  entire  correct- 
ness of  this  assumption.  A  closer  study  of  animal  tis- 
sues under  the  microscope  showed,  particularly  in  the 
case  of  embryonic  tissues,  that  "opaque  spots"  such  as 
Schleiden  described  are  really  to  be  found  there  in 
abundance— forming,  indeed,  a  most  characteristic  phase 
of  the  structure.  The  location  of  these  nuclei  at  com- 
paratively regular  intervals  suggested  that  they  are 
found  in  definite  compartments  of  the  tissue,  as  Schleiden 
had  shown  to  be  the  case  with  vegetables ;  indeed,  the 

O 

walls  that  separated  such  cell- like  compartments  one  from 
another  were  in  some  cases  visible.  Particularly  was 
this  found  to  be  the  case  with  embryonic  tissues,  and 
the  study  of  these  soon  convinced  Schwann  that  his 
original  surmise  had  been  correct,  and  that  all  animal 
tissues  are  in  their  incipiency  composed  of  particles  not 
unlike  the  ultimate  particles  of  vegetables — in  short,  of 
what  the  botanists  termed  cells.  Adopting  this  name, 

332 


KARL   EHNST   VON   BAEK 


PROGRESS   IN   ANATOMY    AND   PHYSIOLOGY 

Schwann  propounded  what  soon  became  famous  as  his 
cell  theory,  under  title  of  MikroskopiscJie  Untersuchun- 
gen  uber  die  Uebereinstimmung  in  der  Structur  und 
dem  Wachsthum  der  Thiere  und  Pflanzen.  So  expeditious 
had  been  his  work,  that  this  book  was  published  early 
in  1839,  only  a  few  months  after  the  appearance  of 
Schleiden's  paper. 

As  the  title  suggests,  the  main  idea  that  actuated 
Schwann  was  to  unify  vegetable  and  animal  tissues. 
Accepting  cell-structure  as  the  basis  of  all  vegetable 
tissues,  he  sought  to  show  that  the  same  is  true  of  ani- 
mal tissues,  all  the  seeming  diversities  of  fibre  being  but 
the  alteration  and  development  of  what  were  originally 
simple  cells.  And  by  cell  Schwann  meant,  as  did  Schlei- 
den  also,  what  the  word  ordinarily  implies  —  a  cavity 
Availed  in  on  all  sides.  He  conceived  that  the  ultimate 
constituents  of  all  tissues  were  really  such  minute  cavi- 
ties, the  most  important  part  of  which  was  the  cell  wall, 
with  its  associated  nucleus.  He  kne\v,  indeed,  that  the 
cell  might  be  filled  with  fluid  contents,  but  he  regarded 
these  as  relatively  subordinate  in  importance  to  the  wall 
itself.  This,  however,  did  not  apply  to  the  nucleus, 
which  was  supposed  to  lie  against  the  cell  wall,  and  in  the 
beginning  to  generate  it.  Subsequently  the  wall  might 
grow  so  rapidly  as  to  dissociate  itself  from  its  contents, 
thus  becoming  a  hollow  bubble  or  true  cell ;  but  the 
nucleus,  as  long  as  it  lasted,  was  supposed  to  continue  in 
contact  with  the  cell  wall.  Schleiden  had  even  supposed 
the  nucleus  to  be  a  constituent  part  of  the  wall,  some- 
times lying  enclosed  between  two  layers  of  its  substance, 
and  Schwann  quoted  this  view  with  seeming  approval. 
Schwann  believed,  however,  that  in  the  mature  cell  the 
nucleus  ceased  to  be  functional,  and  disappeared. 

335 


THE   STORY   OF  NINETEENTH-CENTURY   SCIENCE 

The  main  thesis  as  to  the  similarity  of  development 
of  vegetable  and  animal  tissues,  and  the  cellular  nature 
of  the  ultimate  constitution  of  both,  was  supported  by  a 
mass  of  carefully  gathered  evidence  which  a  multitude 
of  microscopists  at  once  confirmed,  so  Schwann's  work 
became  a  classic  almost  from  the  moment  of  its  publi- 
cation. Of  course  various  other  workers  at  once  dis^ 
puted  Schwann's  claim  to  priority  of  discovery,  in  particu- 
lar the  English  microscopist  Valentin,  who  asserted,  not 
without  some  show  of  justice,  that  he  was  working 
closely  along  the  same  lines.  But  so,  for  that  matter, 
were  numerous  others,  as  Henle,  Turpin,  Dumortier, 
Purkinje,  and  Miiller,  all  of  whom  Schwann  himself  had 
quoted.  Moreover,  there  were  various  physiologists  who 
earlier  than  any  of  these  had  foreshadowed  the  cell  the- 
ory ;  notably  Kaspar  Friedrich  Wolff,  towards  the  close 
of  the  previous  century,  and  Treviranus  about  1807. 
But,  as  we  have  seen  in  so  many  other  departments  of 
science,  it  is  one  thing  to  foreshadow  a  discovery,  it  is 
quite  another  to  give  it  full  expression  and  make  it 
germinal  of  other  discoveries.  And  when  Schwann  put 
forward  the  explicit  claim  that  "  there  is  one  universal 
principle  of  development  for  the  elementary  parts  of 
organisms,  however  different,  and  this  principle  is  the 
formation  of  cells,"  he  enunciated  a  doctrine  which  was 
for  all  practical  purposes  absolutely  new,  and  opened 
up  a  novel  field  for  the  microscopist  to  enter.  A  most 
important  era  in  physiology  dates  from  the  publication 
of  his  book  in  1839. 

IV 

That  Schwann  should  have  gone  to  embryonic  tissues 
for  the  establishment  of  his  ideas  was  no  doubt  due  very 


PROGRESS    IN  ANATOMY   AND  PHYSIOLOGY 

largely  to  the  influence  of  the  great  Russian,  Karl  Ernst 
von  Baer,  who  about  ten  years  earlier  had  published  the 
first  part  of  his  celebrated  work  on  embryology,  and 


JOHANNES   MULLER 


whose  ideas  were  rapidly  gaining  ground,  thanks  large- 
ly to  the  advocacy  of  a  few  men,  notably  Johannes  Miil- 
ler  in  Germany,  and  William  B.  Carpenter  in  England, 
and  to  the  fact  that  the  improved  microscope  had  made 
minute  anatomy  popular.  Schwann's  researches  made 
it  plain  that  the  best  field  for  the  study  of  the  animal 
cell  is  here,  and  a  host  of  explorers  entered  the  field. 
The  result  of  their  observations  was,  in  the  main,  to  eon- 
Y  337. 


THE  STORY  OF  NINETEENTH-CENTURY   SCIENCE 

firm  the  claims  of  Schwann  as  to  the  universal  prev- 
alence of  the  cell.  The  long-current  idea  that  animal 
tissues  grow  only  as  a  sort  of  deposit  from  the  blood- 
vessels was  now  discarded,  and  the  fact  of  so-called 
plant-like  growth  of  animal  cells,  for  which  Schwann 
contended,  was  universally  accepted.  Yet  the  full 
measure  of  the  affinity  between  the  two  classes  of  cells 
was  not  for  some  time  generally  apprehended. 

Indeed,  since  the  substance  that  composes  the  cell 
walls  of  plants  is  manifestly  very  different  from  the 
limiting  membrane  of  the  animal  cell,  it  was  natural,  so 
long  as  the  wall  was  considered  the  most  essential  part 
of  the  structure,  that  the  divergence  between  the  two 
classes  of  cells  should  seem  very  pronounced.  And  for 
a  time  this  was  the  conception  of  the  matter  that  was 
uniformly  accepted.  But  as  time  went  on  many  ob- 
servers had  their  attention  called  to  the  peculiar  char- 
acteristics of  the  contents  of  the  cell,  and  were  led  to 
ask  themselves  whether  these  might  not  be  more  im- 
portant than  had  been  supposed.  In  particular  Dr. 
Hugo  von  Mohl,  professor  of  botany  in  the  university  of 
Tubingen,  in  the  course  of  his  exhaustive  studies  of  the 
vegetable  cell,  was  impressed  with  the  peculiar  and 
characteristic  appearance  of  the  cell  contents.  He  ob- 
served universally  within  the  cell  "  an  opaque,  viscid 
fluid,  having  granules  intermingled  in  it,"  which  made 
up  the  main  substance  of  the  cell,  and  which  particular- 
ly impressed  him  because  under  certain  conditions  it 
could  be  seen  to  be  actively  in  motion,  its  parts  sep- 
arated into  filamentous  streams. 

Yon  Mohl  called  attention  to  the  fact  that  this  mo- 
tion of  the  cell  contents  had  been  observed  as  long  ago 
as  1774  by  Bonaventura  Corti,  and  rediscovered  in  1807 


PROGRESS   IN   ANATOMY    AND   PHYSIOLOGY 


by  Treviranus,  and  that  these  observers  had  described 
the  phenomenon  under  the  u  most  unsuitable  name  of 
'  rotation  of  the  cell  sap.'  r  Yon  Mohl  recognized  that 
the  streaming  substance  was 
something  quite  different 
from  sap.  He  asserted  that 
the  nucleus  of  the  cell  lies 
within  this  substance,  and 
not  attached  to  the  cell  wall 
as  Schleiden  had  contended. 
He  saw,  too,  that  the  chlo- 
rophyl  granules,  and  all 
other  of  the  cell  contents, 
are  incorporated  with  the 
"  opaque,  viscid  fluid,"  and 
in  1846  he  had  become  so 
impressed  with  the  impor- 
tance of  this  universal  cell 
substance  that  he  gave  it 
the  name  of  protoplasm.  Yet  in  so  doing  he  had  no  inten- 
tion of  subordinating  the  cell  wall.  The  fact  that  Payen 
in  1844,  had  demonstrated  that  the  cell  walls  of  all  vege- 
tables, high  or  low,  are  composed  largely  of  one  sub- 
stance, cellulose,  tended  to  strengthen  the  position  of 
the  cell  wall  as  the  really  essential  structure,  of  which 
the  protoplasmic  contents  were  only  subsidiary  prod- 
ucts. 

Meantime,  however,  the  students  of  animal  histology 
were  more  and  more  impressed  with  the  seeming  pre- 
ponderance of  cell  contents  over  cell  walls  in  the  tissues 
they  studied.  They  too  found  the  cell  to  be  filled  with 
a  viscid,  slimy  fluid,  capable  of  motion.  To  this  Du- 
jardin  gave  the  name  of  sarcode.  Presently  it  came  to 

339. 


WILLIAM   HKNJAMIX  CAItPKXTKR 
Photographed  by  Elliot  and  Fry,  Londor 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

be  known,  through  the  labors  of  Kolliker,  Nageli,  Bis- 
choff,  and  various  others,  that  there  are  numerous  lower 
forms  of  animal  life  which  seem  to  be  composed  of  this 
sarcode,  without  any  cell  wall  whatever.  The  same 
thing  seemed  to  be  true  of  certain  cells  of  higher  organ- 
isms, as  the  blood  corpuscles.  Particularly  in  the  case 
of  cells  that  change  their  shape  markedly,  moving  about 
in  consequence  of  the  streaming  of  their  sarcode,  did  it 
seem  certain  that  no  cell  wall  is  present ;  or  that,  if  pres- 
ent, its  role  must  be  insignificant. 

And  so  histologists  came  to  question  whether,  after 
all,  the  cell  contents  rather  than  the  enclosing  wall  must 
not  be  the  really  essential  structure,  and  the  weight  of 
increasing  observations  finally  left  no  escape  from  the 
conclusion  that  such  is  really  the  case.  But  attention 
being  thus  focalized  on  the  cell  contents,  it  was  at  once 
apparent  that  there  is  a  far  closer  similarity  between 
the  ultimate  particles  of  vegetables  and  those  of  ani- 
mals than  had  been  supposed.  Cellulose  and  animal 
membrane  being  now  regarded  as  mere  by-products,  the 
way  was  clear  for  the  recognition  of  the  fact  that  veg- 
etable protoplasm  and  animal  sarcode  are  marvellously 
similar  in  appearance  and  general  properties.  The  closer 
the  observation  the  more  striking  seemed  this  similar- 
ity ;  and  finally,  about  1860,  it  was  demonstrated  by 
Heinrich  de  Bary  and  by  Max  Schultze  that  the  two  are 
to  all  intents  and  purposes  identical.  Even  earlier  Ke- 
mak  had  reached  a  similar  conclusion,  and  applied  von 
Mohl's  word  protoplasm  to  animal  cell  contents,  and 
now  this  application  soon  became  universal.  Thence- 
forth this  protoplasm  was  to  assume  the  utmost  impor- 
tance in  the  physiological  world,  being  recognized  as  the 
universal  "  physical  basis  of  life,"  vegetable  and  animal 

340 


MAX  SCHULTZE 


PROGRESS   IN    ANATOMY   AND   PHYSIOLOGY 

alike.  This  amounted  to  the  logical  extension  and  cul- 
mination of  Schwana's  doctrine  as  to  the  similarity  of 
development  of  the  two  animate  kingdoms.  Yet  at  the 
same  time  it  was  in  effect  the  banishment  of  the  cell 
that  Schwann  had  defined.  The  word  cell  was  retained, 
it  is  true,  but  it  no  longer  signified  a  minute  cavity.  It 
now  implied,  as  Schultze  defined  it,  "  a  small  mass  of 
protoplasm  endowed  with  the  attributes  of  life."  This 
definition  was  destined  presently  to  meet  with  yet  an- 
other modification,  as  we  shall  see ;  but  the  conception 
of  the  protoplasmic  mass  as  the  essential  ultimate  struct- 
ure, which  might  or  might  not  surround  itself  with  a 
protective  covering,  was  a  permanent  addition  to  physi- 
ological knowledge.  The  earlier  idea  had,  in  effect,  de- 
clared the  shell  the  most  important  part  of  the  egg; 
this  developed  view  assigned  to  the  yolk  its  true  posi- 
tion. 

In  one  other  important  regard  the  theory  of  Schleiden 
and  Schwann  now  became  modified.  This  referred  to 
the  origin  of  the  cell.  Schwann  had  regarded  cell 
growth  as  a  kind  of  crystallization,  beginning  with  the 
deposit  of  a  nucleus  about  a  granule  in  the  intercellular 
substance  —  the  cytoblastema,  as  Schleiden  called  it. 
But  von  Mohl,  as  early  as  1835,  had  called  attention  to 
the  formation  of  new  vegetable  cells  through  the  divis- 
ion of  a  pre-existing  cell.  Ehrenberg,  another  high  au- 
thority of  the  time,  contended  that  no  such  division  oc- 
curs, and  the  matter  was  still  in  dispute  when  Schleiden 
came  forward  with  his  discovery  of  so-called  free  cell 
formation  within  the  parent  cell,  and  this  for  a  long 
time  diverted  attention  from  the  process  of  division 
which  von  Mohl  had  described.  All  manner  of  schemes 
of  cell  formation  were  put  forward  during  the  ensuing 

343 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

years  by  a  multitude  of  observers,  and  gained  currency 
notwithstanding  von  Mohl's  reiterated  contention  that 
there  are  really  but  two  ways  in  which  the  formation 
of  new  cells  takes  place,  namely,  "first,  through  divis- 
ion of  older  cells ;  secondly,  through  the  formation  of 
secondary  cells  lying  free  in  the  cavity  of  a  cell." 


HUGO   VON    MOIIL 


But  gradually  the  researches  of  such  accurate  observ- 
ers as  linger,  Nageli,  Kolliker,  Reichart,  and  Remak 
tended  to  confirm  the  opinion  of  von  Molil  that  cells 
spring  only  from  cells,  and  finally  Rudolf  Virchow 
brought  the  matter  to  demonstration  about  1860.  His 

344 


PROGRESS   IN   ANATOMY   AND   PHYSIOLOGY 

Omnis  cellula  e  cellula  became  from  that  time  one  of 
the  accepted  data  of  physiology.  This  was  supplement- 
ed a  little  later  by  Fleming's  Omnis  nucleus  e  nudeo, 
when  still  more  refined  methods  of  observation  had 
shown  that  the  part  of  the  cell  which  always  first  under- 
goes change  preparatory  to  new  cell  formation  is  the  all- 
essential  nucleus.  Thus  the  nucleus  was  restored  to  the 
important  position  which  Schwann  and  Schleiden  had 
given  it,  but  with  greatly  altered  significance.  Instead 
of  being  a  structure  generated  de  novo  from  non-cellular 
substance,  and  disappearing  as  soon  as  its  function  of 
cell-formation  was  accomplished,  the  nucleus  was  now 
known  as  the  central  and  permanent  feature  of  every 
cell,  indestructible  while  the  cell  lives ;  itself  the  divis- 
ion-product of  a  pre-existing  nucleus,  and  the  parent,  by 
division  of  its  substance,  of  other  generations  of  nuclei. 
The  word  cell  received  a  final  definition  as  "a  small 
mass  of  protoplasm  supplied  with  a  nucleus." 

In  this  widened  and  culminating  general  view  of  the 
cell  theory  it  became  clear  that  every  animate  organism, 
animal  or  vegetable,  is  but  a  cluster  of  nucleated  cells,  all 
of  which,  in  each  individual  case,  are  the  direct  descendants 
of  a  single  primordial  cell  of  the  ovum.  In  the  devel- 
oped individuals  of  higher  organisms  the  successive  gen- 
erations of  cells  become  marvellously  diversified  in  form 
and  in  specific  functions;  there  is  a  wonderful  division 
of  labor,  special  functions  being  chiefly  relegated  to  defi- 
nite groups  of  cells;  but  from  first  to  last  there  is  no 
function  developed  that  is  not  present,  in  a  primitive 
way,  in  every  cell,  however  isolated  ;  nor  does  the  de- 
veloped cell,  however  specialized,  ever  forget  altogether 
any  one  of  its  primordial  functions  or  capacities.  All 
physiology,  then,  properly  interpreted,  becomes  merely 

345 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

a  study  of  cellular  activities ;  and  the  development  of 
the  cell  theory  takes  its  place  as  the  great  central  gen- 
eralization in  physiology  of  our  century.  Something  of 
the  later  developments  of  this  theory  we  shall  see  in  an- 
other connection. 

v 

Just  at  the  time  when  the  microscope  was  opening 
up  the  paths  that  were  to  lead  to  the  wonderful  cell 
theory,  another  novel  line  of  interrogation  of  the  liv- 
ing organism  was  being 
put  forward  by  a  differ- 
ent set  of  observers.  Two 
great  schools  of  physio- 
logical chemistry  had  arisen 
-one  under  guidance  of 
Liebig  and  Wohler  in  Ger- 
many, the  other  dominated 
by  the  great  French  master 
Jean  Baptiste  Dumas.  Lie- 
big  had  at  one  time  contem- 
plated the  study  of  medicine, 
and  Dumas  had  achieved  dis- 
tinction in  connection  with 
Prevost  at  Geneva  in  the 
field  of  pure  physiology  be- 
fore he  turned  his  attention  especially  to  chemistry.  Both 
these  masters,  therefore,  and  Wohler  as  well,  found  ab- 
sorbing interest  in  those  phases  of  chemistry  that  have 
to  do  with  the  functions  of  living  tissues;  and  it  was 
largely  through  their  efforts  and  the  labors  of  their  fol- 
lowers that  the  prevalent  idea  that  vital  processes  are 
dominated  by  unique  laws  was  discarded  and  physiology 

346 


JEAX   BAPTISTE    DUMAS 


PROGRESS   IN   ANATOMY    AND   PHYSIOLOGY 

was  brought  within  the  recognized  province  of  the 
chemist.  So  at  about  the  time  when  the  microscope 
had  taught  that  the  cell  is  the  really  essential  structure 
of  the  living  organism,  the  chemists  had  come  to  under- 
stand that  every  function  of  the  organism  is  really  the 
expression  of  a  chemical  change — that  each  cell  is,  in 
short,  a  miniature  chemical  laboratory.  And  it  was 
this  combined  point  of  view  of  anatomist  and  chemist, 
this  union  of  hitherto  dissociated  forces,  that  made  pos- 
sible the  inroads  into  the  unexplored  fields  of  physi- 
ology that  were  effected  towards  the  middle  of  our  cen- 
tury. 

One  of  the  first  subjects  reinvestigated  and  brought 
to  proximal  solution  was  the  long-mooted  question  of 
the  digestion  of  foods.  Spallanzani  and  Hunter  had 
shown  in  the  previous  century  that  digestion  is  in  some 
sort  a  solution  of  foods ;  but  little  advance  was  made 
upon  their  work  until  1824,  when  Prout  detected  the 
presence  of  hydrochloric  acid  in  the  gastric  juice.  A 
decade  later  Sprott  and  Boyd  detected  the  existence  of 
peculiar  glands  in  the  gastric  mucous  membrane;  and 
Cagniard  la  Tour  and  Schwann  independently  discov- 
ered that  the  really  active  principle  of  the  gastric  juice 
is  a  substance  which  was  named  pepsin,  and  which  was 
shown  by  Schwann  to  be  active  in  the  presence  of  hy- 
drochloric acid. 

Almost  coincidently,  in  1836,  it  was  discovered  by 
Purkinje  and  Pappenheim  that  another  organ  than  the 
stomach — the  pancreas,  namely — has  a  share  in  diges- 
tion, and  in  the  course  of  the  ensuing  decade  it  came  to 
be  known,  through  the  efforts  of  Eberle,  Valentin,  and 
Claude  Bernard,  that  this  organ  is  all-important  in  the 
digestion  of  starchy  and  fatty  foods.  It  was  found,  too, 

347 


THE   STORY  OF   NINETEENTH-CENTURY  SCIENCE 

that  the  liver  and  the  intestinal  glands  have  each  an  im- 
portant share  in  the  work  of  preparing  foods  for  absorp- 
tion, as  also  has  the  saliva — that,  in  short,  a  coalition  of 
forces  is  necessary  for  the  digestion  of  all  ordinary  foods 
taken  into  the  stomach. 

And  the  chemists  soon  discovered  that  in  each  one  of 
the  essential  digestive  juices  there  is  at  least  one  sub- 
stance having  certain  resemblances  to  pepsin,  though 
acting  on  different  kinds  of  food.  The  point  of  resem- 
blance between  all  these  essential  digestive  agents  is 
that  each  has  the  remarkable  property  of  acting  on 
relatively  enormous  quantities  of  the  substance  which 
it  can  digest  without  itself  being  destroyed  or  apparent- 
ly even  altered.  In  virtue  of  this  strange  property, 
pepsin  and  the  allied  substances  were  spoken  of  as  fer- 
ments, but  more  recently  it  is  customary  to  distingush 
them  from  such  organized  ferments  as  yeast  by  desig- 
nating them  enzymes.  The  isolation  of  these  enzymes, 
and  an  appreciation  of  their  mode  of  action,  mark  a 
long  step  towards  the  solution  of  the  riddle  of 'digestion, 
but  it  must  be  added  that  we  are  still  quite  in  the  dark 
as  to  the  real  ultimate  nature  of  their  strange  activity. 

In  a  comprehensive  view,  the  digestive  organs,  taken 
as  a  whole,  are  a  gateway  between  the  outside  world 
and  the  more  intimate  cells  of  the  organism.  Another 
equally  important  gateway  is  furnished  by  the  lungs, 
and  here  also  there  was  much  obscurity  about  the  exact 
method  of  functioning  at  the  time  of  the  revival  of  phys- 
iological chemistry.  That  oxygen  is  consumed  and 
carbonic  acid  given  off  during  respiration  the  chemists 
of  the  age  of  Priestley  and  Lavoisier  had  indeed  made 
clear,  but  the  mistaken  notion  prevailed  that  it  was  in 
the  lungs  themselves  that  the  important  burning  of  fuel 

348 


PROGRESS   IN   ANATOMY   AND   PHYSIOLOGY 

occurs,  of  which  carbonic  acid  is  a  chief  product.  But 
now  that  attention  had  been  called  to  the  importance  of 
the  ultimate  cell,  this  misconception  could  not  long  hold 
its  ground,  and  as  early  as  1842  Liebig,  in  the  course  of 
his  studies  of  animal  heat,  became  convinced  that  it  is 
not  in  the  lungs,  but  in  the  ultimate  tissues  to  which 
they  are  tributary,  that  the  true  consumption  of  fuel 
takes  place.  Reviving  Lavoisier's  idea,  with  modifica- 
tions and  additions,  Liebig  contended,  and  in  the  face 
of  opposition  finally  demonstrated,  that  the  source  of 
animal  heat  is  really  the  consumption  of  the  fuel  taken 
in  through  the  stomach  and  the  lungs.  He  showed 
that  all  the  activities  of  life  are  really  the  product  of 
energy  liberated  solely  through  destructive  processes, 
amounting,  broadly  speaking,  to  combustion  occurring 
in  the  ultimate  cells  of  the  organism. 

Further  researches  showed  that  the  carriers  of  oxy- 
gen, from  the  time  of  its  absorption  in  the  lungs  till  its 
liberation  in  the  ultimate  tissues,  are  the  red  corpuscles, 
whose  function  had  been  supposed  to  be  the  mechanical 
one  of  mixing  of  the  blood.  It  transpired  that  the  red 
corpuscles  are  composed  chiefly  of  a  substance  which 
Kiihne  first  isolated  in  crystalline  form  in  1865,  and 
which  was  named  haemoglobin — a  substance  which  has 
a  marvellous  affinity  for  oxygen,  seizing  on  it  eagerly 
at  the  lungs,  yet  giving  it  up  with  equal  readiness  when 
coursing  among  the  remote  cells  of  the  body.  When 
freighted  with  oxygen  it  becomes  oxy haemoglobin,  and 
is  red  in  color ;  Avhen  freed  from  its  oxygen  it  takes  a 
purple  hue;  hence  the  widely  different  appearance  of 
arterial  and  venous  blood,  which  so  puzzled  the  early 
physiologists. 

This  proof  of  the  vitally  important  role  played  by  the 

349 


THE  STORY  Otf  NINETEENTH-CENTURY  SCIENCE 

red  blood  corpuscles  led,  naturally,  to  renewed  studies 
of  these  infinitesimal  bodies.  It  was  found  that  they 
may  vary  greatly  in  number  at  different  periods  in  the 
life  of  the  same  individual,  proving  that  they  may  be 
both  developed  and  destroyed  in  the  adult  organism. 
Indeed,  extended  observations  left  no  reason  to  doubt 
that  the  process  of  corpuscle  formation  and  destruction 
may  be  a  perfectly  normal  one ;  that,  in  short,  every 
red  blood  corpuscle  runs  its  course  and  dies  like  any 
more  elaborate  organism.  They  are  formed  constantly 
in  the  red  marrow  of  bones,  and  are  destroyed  in  the 
liver,  where  they  contribute  to  the  formation  of  the 
coloring  matter  of  the  bile.  Whether  there  are  other 
seats  of  such  manufacture  and  destruction  of  the  cor- 
puscles is  not  yet  fully  determined.  Nor  are  histolo- 
gists  agreed  as  to  whether  the  red  blood  corpuscles 
themselves  are  to  be  regarded  as  true  cells,  or  merely  as 
fragments  of  cells  budded  out  from  a  true  cell  for  a 
special  purpose ;  but,  in  either  case,  there  is  not  the 
slightest  doubt  that  the  chief  function  of  the  red  cor- 

O 

puscle  is  to  carry  oxygen. 

If  the  oxygen  is  taken  to  the  ultimate  cells  before 
combining  with  the  combustibles  it  is  to  consume,  it 
goes  without  saying  that  these  combustibles  themselves 
must  be  carried  there  also.  Nor  could  it  be  in  doubt 
that  the  chief est  of  these  ultimate  tissues,  as  regards 
quantity  of  fuel  required,  are  the  muscles.  A  general 
and  comprehensive  view  of  the  organism  includes,  then, 
digestive  apparatus  and  lungs  as  the  channels  of  fuel- 
supply  ;  blood  and  lymph  channels  as  the  transportation 
system;  and, muscle  cells,  united  into  muscle  fibres,  as 
the  consumption  furnaces,  where  fuel  is  burned  and 
energy  transformed  and  rendered  available  for  the  pur- 

^350 


PROGRESS   IN  ANATOMY   AND  PHYSIOLOGY 


poses  of  the  organism,  supplemented  by  a  set  of  ex- 
cretory organs,  through  which  the  waste  products — 
the  ashes — are  eliminated  from  the  system. 

But  there  remain,  broadly 
speaking,  two  other  sets  of 
organs  whose  size  demon- 
strates their  importance  in 
the  economy  of  the  organ- 
ism, yet  whose  functions  are 
not  accounted  for  in  this 
synopsis.  These  are  those 
gland  like  organs,  such  as  the 
spleen,  which  have  no  duct 
and  produce  no  visible  se- 
cretions ;  and  the  nervous 
mechanism,  whose  central 
organs  are  the  brain  and 
spinal  cord.  What  offices 
do  these  sets  of  organs  per- 
form in  the  great  labor-specializing  aggregation  of  cells 
which  we  call  a  living  organism? 

As  regards  the  ductless  glands,  the  first  clew  to  their 
function  was  given  when  the  great  Frenchman  Claude 
Bernard  (the  man  of  whom  his  admirers  loved  to  say, 
"  he  is  not  a  physiologist  merely ;  he  is  physiology  it- 
self ")  discovered  what  is  spoken  of  as  the  glycogenic 
function  of  the  liver.  The  liver  itself,  indeed,  is  not  a 
ductless  organ,  but  the  quantity  of  its  biliary  output 
seems  utterly  disproportionate  to  its  enormous  size,  par- 
ticularly when  it  is  considered  that  in  the  case  of  the 
human  species  the  liver  contains  normally  about  one- 
fifth  of  all  the  blood  in  the  entire  body.  Bernard  dis- 
covered that  the  blood  undergoes  a  change  of  composi- 

..  351 


CLAUDE    BERNARD 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

tion  in  passing  through  the  liver.  The  liver  cells  (the 
peculiar  forms  of  which  had  been  described  by  Purkinje, 
Henle,  and  Dutrochet  about  1838)  have  the  power  to 
convert  certain  of  the  substances  that  come  to  them  into 
a  starchlike  compound  called  glycogen,  and  to  store  this 
substance  away  till  it  is  needed  by  the  organism.  This 
capacity  of  the  liver  cells  is  quite  independent  of  the 
bile-making  power  of  the  same  cells ;  hence  the  discov- 
ery of  this  glycogenic  function  showed  that  an  organ 
may  have  more  than  one  pronounced  and  important 
specific  function.  But  its  chief  importance  was  in  giv- 
ing a  clew  to  those  intermediate  processes  between  di- 
gestion and  final  assimilation  that  are  now  known  to 
be  of  such  vital  significance  in  the  economy  of  the  or- 
ganism. 

In  the  forty-odd  years  that  have  elapsed  since  this 
pioneer  observation  of  Bernard,  numerous  facts  have 
come  to  light  showing  the  extreme  importance  of  such 
intermediate  alterations  of  food-supplies  in  the  blood  as 
that  performed  by  the  liver.  It  has  been  shown  that 
the  pancreas,  the  spleen,  the  thyroid  gland,  the  supra- 
renal capsules  are  absolutely  essential,  each  in  its  own 
way,  to  the  health  of  the  organism,  through  metabolic 
changes  which  they  alone  seem  capable  of  performing ; 
and  it  is  suspected  that  various  other  tissues,  including 
even  the  muscles  themselves,  have  somewhat  similar 
metabolic  capacities  in  addition  to  their  recognized  func- 
tions. But  so  extremely  intricate  is  the  chemistry  of 
the  substances  involved  that  in  no  single  case  has  the  ex- 
act nature  of  the  metabolisms  wrought  by  these  organs 
been  fully  made  out.  Each  is  in  its  way  a  chemical 
laboratory  indispensable  to  the  right  conduct  of  the 
organism,  but  the  precise  nature  of  its  operations  re- 

352   . 


PROGRESS   IN   ANATOMY   AND   PHYSIOLOGY 

mains  inscrutable.     The  vast  importance  of  the  opera- 
tions of  these  intermediate  organs  is  unquestioned. 

A  consideration  of  the  functions  of  that  other  set  of 
organs  known  collectively  as  the  nervous  system  is  re- 
served for  a  later  chapter. 


CHAPTER  XI 
THE  CENTURY'S   PROGRESS    IN   SCIENTIFIC   MEDICINE 


ALTHOUGH  Napoleon  Bonaparte,  First  Consul,  was  not 
lacking  in  self-appreciation,  he  probably  did  not  realize 
that  in  selecting  a  physician  for  his  own  needs  he  was 
markedly  influencing  the  progress  of  medical  science  as 
a  whole.  Yet  so  strangely  are  cause  and  effect  ad- 
justed in  human  affairs  that  this  simple  act  of  the  First 
Consul  had  that  very  unexpected  effect.  For  the  man 
chosen  was  the  envoy  of  a  new  method  in  medical  prac- 
tice, and  the  fame  which  came  to  him  through  being 
physician  to  the  First  Consul,  and  subsequently  to  the 
Emperor,  enabled  him  to  promulgate  the  method  in  a 
way  otherwise  impracticable.  Hence  the  indirect  but 
telling  value  to  medical  science  of  Napoleon's  selection. 

The  physician  in  question  was  Jean  Nicolas  de  Corvi- 
sart.  His  novel  method  was  nothing  more  startling 
than  the  now  familiar  procedure  of  tapping  the  chest  of 
a  patient  to  elicit  sounds  indicative  of  diseased  tissues 
within.  Every  one  has  seen  this  done  commonly 
enough  in  our  day,  but  at  the  beginning  of  the  century 
Corvisart,  and  perhaps  some  of  his  pupils,  were  proba- 
bly the  only  physicians  in  the  world  who  resorted  to 

354 


CENTURY'S    PROGRESS   IN    SCIENTIFIC  MEDICINE 

this  simple  and  useful  procedure.  Hence  Napoleon's 
surprise  when,  on  calling  in  Corvisart,  after  becoming 
somewhat  dissatisfied  with  his  other  physicians,  Pinel 
and  Portal,  his  physical  condition  was  interrogated  in 
this  strange  manner.  With  characteristic  shrewdness 
Bonaparte  saw  the  utility  of  the  method,  and  the  physi- 
cian  who  thus  attempted  to  substitute  scientific  method 
for  guess-work  in  the  diagnosis  of  disease  at  once  found 
favor  in  his  eyes,  and  was  installed  as  his  regular  medi- 
cal adviser. 

For  fifteen  years  before  this  Corvisart  had  practised 
percussion,  as  the  chest-tapping  method  is  called,  with- 
out succeeding  in  convincing  the  profession  of  its  value. 
The  method  itself,  it  should  be  added,  had  not  origi- 
nated with  Corvisart,  nor  did  the  French  physician  for  a 
moment  claim  it  as  his  own.  The  true  originator  of  the 
practice  was  the  German  physician  Avenbrugger,  who 
published  a  oook  about  it  as  early  as  1761.  This  book 
had  even  been  translated  into  French,  then  the  language 
of  international  communication  everywhere,  by  Roziere 
de  la  Chassagne,  of  Montpellier,  in  1770 ;  but  no  one 
other  than  Corvisart  appears  to  have  paid  any  attention 
to  either  original  or  translation.  It  was  far  otherwise, 
however,  when  Corvisart  translated  Avenbrugger's  work 
anew,  with  important  additions  of  his  own,  in  1808.  By 
this  time  a  reaction  had  set  in  against  the  metaphysical 
methods  in  medicine  that  had  previously  been  so  allur- 
ing; the  scientific  spirit  of  the  time  was  making  itself  felt 
in  medical  practice;  and  this,  combined  with  Corvisart's 
fame,  brought  the  method  of  percussion  into  immediate 
and  well-deserved  popularity.  Thus  was  laid  the  foun- 
dation for  the  method  of  so-called  physical  diagnosis, 
which  is  one  of  the  corner-stones  of  modern  medicine. 

355^ 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

The  method  of  physical  diagnosis  as  practised  in  our 
day  was  by  no  means  completed,  however,  with  the 
work  of  Corvisart.  Percussion  alone  tells  much  less 
than  half  the  story  that  may  be  elicited  from  the  organs 
of  the  chest  by  proper  interrogation.  The  remainder  of 
the  story  can  only  be  learned  by  applying  the  ear  itself 
to  the  chest,  directly  or  indirectly.  Simple  as  this 
seems,  no  one  thought  of  practising  it  for  some  years 
after  Corvisart  had  shown  the  value  of  percussion. 
Then,  in  1815,  another  Paris  physician,  Eene  Theophile 
Hyacinthe  Laennec,  discovered,  almost  by  accident,  that 
the  sound  of  the  heart-beat  could  be  heard  surprisingly 
through  a  cylinder  of  paper  held  to  the  ear  and  against 
the  patient's  chest.  Acting  on  the  hint  thus  received, 
Laennec  substituted  a  hollow  cylinder  of  wood  for  the 
paper,  and  found  himself  provided  with  an  instrument 
through  which  not  merely  heart  sounds,  but  murmurs 
of  the  lungs  in  respiration,  could  be  heard  with  almost 
startling  distinctness. 

The  possibility  of  associating  the  varying  chest  sounds 
with  diseased  conditions  of  the  organs  within  appealed 
to  the  fertile  mind  of  Laennec  as  opening  new  vistas  in 
therapeutics,  which  he  determined  to  enter  to  the  fullest 
extent  practicable.  His  connection  with  the  hospitals  of 
Paris  gave  him  full  opportunity  in  this  direction,  and  his 
labors  of  the  next  few  years  served  not  merely  to  estab- 
lish the  value  of  the  new  method  as  an  aid  to  diagnosis, 
but  laid  the  foundation  also  for  the  science  of  morbid 
anatomy.  In  1819  Laennec  published  the  results  of  his 
labors  in  a  work  called  Traite  d?  Auscultation  Mediate, 
a  work  which  forms  one  of  the  landmarks  of  scientific 
medicine.  By  mediate  auscultation  is  meant  of  course 
the  interrogation  of  the  chest  with  the  aid  of  the  little 

356 


LAENNEC,  INVENTOR  OF  THE   STETHOSCOPE,   AT  THE   NECKER  HOSPITAL, 

PAIUS 


CENTURY'S   PROGRESS   IN   SCIENTIFIC   MEDICINE 

instrument  already  referred  to,  an  instrument  which  its 
originator  thought  hardly  worth  naming  until  various 
barbarous  appellations  were  applied  to  it  by  others,  after 
which  Laennec  decided  to  call  it  the  stethoscope,  a  name 
which  it  has  ever  since  retained. 

In  subsequent  years  the  form  of  the  stethoscope,  as 
usually  employed,  was  modified,  and  its  value  augment- 
ed by  a  binauricular  attachment;  and  in  very  recent 
years  a  further  improvement  has  been  made  through  ap- 
plication of  the  principle  of  the  telephone ;  but  the  es- 
sentials of  auscultation  with  the  stethoscope  were  estab- 
lished in  much  detail  by  Laennec,  and  the  honor  must 
always  be  his  of  thus  taking  one  of  the  longest  single 
steps  by  which  practical  medicine  has  in  our  century  ac- 
quired the  right  to  be  considered  a  rational  science. 
Laennec' s  efforts  cost  him  his  life,  for  he  died  in  1826 
of  a  lung  disease  acquired  in  the  course  of  his  hospital 
practice ;  but  even  before  this  his  fame  was  universal, 
and  the  value  of  his  method  had  been  recognized  all 
over  the  world.  Not  long  after,  in  1828,  yet  another 
French  physician,  Piorry,  perfected  the  method  of  per- 
cussion by  introducing  the  custom  of  tapping,  not  the 
chest  directly,  but  the  finger  or  a  small  metal  or  hard 
rubber  plate  held  against  the  chest — mediate  percussion, 
in  short.  This  perfected  the  methods  of  physical  diag- 
nosis of  diseases  of  the  chest  in  all  essentials ;  and  from 
that  day  till  this  percussion  and  auscultation  have  held 
an  unquestioned  place  in  the  regular  armamentarium  of 
the  physician. 

Coupled  with  the  new  method  of  physical  diagnosis 
in  the  effort  to  substitute  knowledge  for  guess-work 
came  the  studies  of  the  experimental  physiologists — in 
particular,  Marshall  Hall  in  England,  and  Francois  Ma- 

359 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

gendie  in  France ;  and  the  joint  efforts  of  these  various 
workers  led  presently  to  the  abandonment  of  those  se- 
vere  and  often  irrational  depletive  methods — blood-let- 
ting and  the  like — that  had  previously  dominated  med- 
ical practice.  To  this  end  also  the  "  statistical  method," 
introduced  by  Louis  and  his  followers,  largely  contrib- 
uted ;  and  by  the  close  of  the  first  third  of  our  century 
the  idea  was  gaining  ground  that  the  province  of  thera- 
peutics is  to  aid  nature  in  combating  disease,  and  that 
this  may  often  be  better  accomplished  by  simple  means 
than  by  the  heroic  measures  hitherto  thought  necessary. 
In  a  word,  scientific  empiricism  was  beginning  to  gain  a 
hearing  in  medicine,  as  against  the  metaphysical  precon- 
ceptions of  the  earlier  generations. 


ii 

I  have  just  adverted  to  the  fact  that  Napoleon  Bona- 
parte, as  First  Consul  and  as  Emperor,  was  the  victim 
of  a  malady  which  caused  him  to  seek  the  advice  of  the 
most  distinguished  physicians  of  Paris.  It  is  a  little 
shocking  to  modern  sensibilities  to  read  that  these 
physicians,  except  Corvisart,  diagnosed  the  distinguished 
patient's  malady  as  "  gale  repercutee  " — that  is  to  say, 
in  idiomatic  English,  the  itch  "struck  in."  It  is  hardly 
necessary  to  say  that  no  physician  of  to-day  would 
make  so  inconsiderate  a  diagnosis  in  the  case  of  a  royal 
patient.  If  by  any  chance  a  distinguished  patient  were 
afflicted  with  the  itch,  the  sagacious  physician  would 
carefully  hide  the  fact  behind  circumlocutions,  and  pro- 
ceed to  eradicate  the  disease  with  all  despatch.  That 
the  physicians  of  Napoleon  did  otherwise  is  evidence 
that  at  the  beginning  of  the  century  the  disease  in  ques- 

360 


CENTURY'S   PROGRESS   IN   SCIENTIFIC   MEDICINE 

tion  enjoyed  a  very  different  status.  At  that  time,  itch, 
instead  of  being  a  most  plebeian  malady,  was,  so  to  say,  a 
court  disease.  It  enjoyed  a  circulation,  in  high  circles 
and  in  low,  that  modern  therapeutics  has  quite  denied 
it ;  and  the  physicians  of  the  time  gave  it  a  fictitious 
added  importance  by  ascribing  to  its  influence  the  ex- 
istence of  almost  any  obscure  malady  that  came  under 
their  observation.  Long  after  Napoleon's  time,  gale 
continued  to  hold  this  proud  distinction.  For  example, 
the  imaginative  Dr.  Hahnemann  did  not  hesitate  to  af- 
firm, as  a  positive  maxim,  that  three-fourths  of  all  the 
ills  that  flesh  is  heir  to  were  in  reality  nothing  but  va- 
rious forms  of  "  gale  repercutee." 

All  of  which  goes  to  show  how  easy  it  may  be  for  a 
masked  pretender  to  impose  on  credulous  humanity ;  for 
nothing  is  more  clearly  established  in  modern  knowl- 
edge than  the  fact  that  "gale  repercutee  "  was  simply  a 
name  to  hide  a  profound  ignorance ;  no  such  disease  ex- 
ists, or  ever  did  exist.  Gale  itself  is  a  sufficiently  tangi- 
ble reality,  to  be  sure ;  but  it  is  a  purely  local  disease  of 
the  skin,  due  to  a  perfectly  definite  cause,  and  the  dire 
internal  conditions  formerly  ascribed  to  it  have  really  no 
causal  connection  with  it  whatever.  This  definite  cause, 
as  every  one  nowadays  knows,  is  nothing  more  or  less 
than  a  microscopic  insect  which  has  found  lodgment  on 
the  skin,  and  has  burrowed  and  made  itself  at  home 
there.  Kill  that  insect,  and  the  disease  is  no  more . 
hence  it  has  come  to  be  an  axiom  with  the  modern 
physician  that  the  itch  is  one  of  the  three  or  four  dis- 
eases that  he  positively  is  able  to  cure,  and  that  very 
speedily.  But  it  was  far  otherwise  with  the  physicians 
of  the  first  third  of  our  century,  because  to  them  the 
cause  of  the  disease  was  an  absolute  mystery. 

361 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

It  is  true  that  here  and  there  a  physician  had  claimed 
to  find  an  insect  lodged  in  the  skin  of  a  sufferer  from 
itch,  and  two  or  three  times  the  claim  had  been  made 
that  this  was  the  cause  of  the  malady,  but  such  views 
were  quite  ignored  by  the  general  profession,  and  in 
1833  it  was  stated  in  an  authoritative  medical  treatise 
that  the  "cause  of  gale  is  absolutely  unknown."  But 
even  at  this  time,  as  it  curiously  happened,  there  were 
certain  ignorant  laymen  who  had  attained  to  a  bit  of 
medical  knowledge  that  was  withheld  from  the  inner 

O 

circles  of  the  profession.  As  the  peasantry  of  England 
before  Jenner  had  known  of  the  curative  value  of  cow- 
pox  over  small-pox,  so  the  peasant  women  of  Poland 
had  learned  that  the  annoying  skin  disease  from  which 
they  suffered  was  caused  by  an  almost  invisible  insect, 
and,  furthermore,  had  acquired  the  trick  of  dislodging 
the  pestiferous  little  creature  with  the  point  of  a  needle. 
From  them  a  youth  of  the  country,  F.  Renucci  by 
name,  learned  the  open  secret.  He  conveyed  it  to  Paris 
when  he  went  there  to  study  medicine,  and  in  183^ 
demonstrated  it  to  his  master,  Alibert.  This  physician, 
at  first  sceptical,  soon  was  convinced,  and  gave  out  the 
discovery  to  the  medical  world  with  an  authority  that 
led  to  early  acceptance. 

Now  the  importance  of  all  this,  in  the  present  con- 
nection, is  not  at  all  that  it  gave  the  clew  to  the  method 
of  cure  of  a  single  disease.  What  makes  the  discovery 
epochal  is  the  fact  that  it  dropped  a  brand-new  idea 
into  the  medical  ranks — an  idea  destined,  in  the  long- 
run,  to  prove  itself  a  veritable  bomb — the  idea,  namely, 
that  a  minute  and  quite  unsuspected  animal  parasite 
may  be  the  cause  of  a  well-known,  widely  prevalent, 
and  important  human  disease.  Of  course  the  full  force 

362 


CENTURY'S   PROGRESS   IN   SCIENTIFIC    MEDICINE 

of  this  idea  could  only  be  appreciated  in  the  light  of 
later  knowledge ;  but  even  at  the  time  of  its  coming  it 
sufficed  to  give  a  great  impetus  to  that  new  medical 
knowledge,  based  on  microscopical  studies,  which  had 
but  recently  been  made  accessible  by  the  inventions 
of  the  lens-makers.  The  new  knowledge  clarified  one 
very  turbid  medical  pool,  and  pointed  the  way  to  the 
clarification  of  many  others. 

Almost  at  the  same  time  that  the  Polish  medical  stu- 
dent was  demonstrating  the  itch  mite  in  Paris,  it 
chanced,  curiously  enough,  that  another  medical  stu- 
dent, this  time  an  Englishman,  made  an  analogous  dis- 
covery, of  perhaps  even  greater  importance.  Indeed, 
this  English  discovery  in  its  initial  stages  slightly  ante- 
dated the  other,  for  it  was  in  1833  that  the  student  in 
question,  James  Paget,  interne  in  Saint  Bartholomew's 
Hospital,  London,  while  dissecting  the  muscular  tissues 
of  a  human  subject,  found  little  specks  of  extraneous 
matter,  which,  when  taken  to  the  professor  of  compara- 
tive anatomy,  Richard  Owen,  were  ascertained,  with  the 
aid  of  the  microscope,  to  be  the  cocoon  of  a  minute  and 
hitherto  unknown  insect.  Owen  named  the  insect  Tri- 
china spiralis.  After  the  discovery  was  published,  it 
transpired  that  similar  specks  had  been  observed  by 
several  earlier  investigators,  but  no  one  had  previously 
suspected,  or,  at  any  rate,  demonstrated  their  nature. 
Nor  was  the  full  story  of  the  trichina  made  out  for  a 
long  time  after  Owen's  discovery.  It  was  not  till  1847 
that  the  American  anatomist  Dr.  Joseph  Leidy  found 
the  cysts  of  trichina  in  the  tissues  of  pork ;  and  another 
decade  or  so  elapsed  after  that  before  German  workers, 
chief  among  whom  were  Leuckart,  Yirchow,  and  Zen- 
ker,  proved  that  the  parasite  gets  into  the  human  sys- 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

tein   through   ingestion    of  infected  pork,  and  that  it 
causes  a  definite  set  of  symptons  of  disease,  which  hith- 


RUDOLF  VIRCHOW 

erto  had  been  mistaken  for  rheumatism,  typhoid  fever, 
and  other  maladies.  Then  the  medical  world  was  agog 
for  a  time  over  the  subject  of  trichinosis  ;  government  in- 
spection of  pork  was  established  in  some  parts  of  Ger- 

364 


CENTURY'S  PROGRESS   IN  SCIENTIF:C   MEDICINE 

many ;  American  pork  was  excluded  altogether  from 
France ;  and  the  whole  subject  thus  came  prominently  to 
public  attention.  But  important  as  the  trichina  parasite 
proved  on  its  own  account  in  the  end,  its  greatest  im- 
portance, after  all.  was  in  the  share  it  played  in  direct- 
ing attention  at  the  time  of  its  discovery  in  1833  to  the 
subject  of  microscopic  parasites  in  general. 

The  decade  that  followed  that  discovery  was  a  time 
of  great  activity  in  the  study  of  microscopic  organisms 
and  microscopic  tissues,  and  such  men  as  Ehrenberg  and 
Henle  and  Bory  Saint  Vincent  and  Kolliker  and  Roki- 
tansky  and  Remak  and  Dujardin  were  widening  the 
bounds  of  knowledge  of  this  new  subject  with  details 
that  cannot  be  more  than  referred  to  here.  But  the 
crowning  achievement  of  the  period  in  this  direction 
was  the  discovery  made  by  the  German  J.  L.  Schoen- 
lein  in  1839,  that  a  very  common  and  most  distressing 
disease  of  the  scalp,  known  as  favus,  is  really  due  to  the 
presence  and  growth  on  the  scalp  of  a  vegetable  organ- 
ism of  microscopic  size.  Thus  it  was  made  clear  that 
not  merely  animal  but  also  vegetable  organisms  of  ob- 
scure, microscopic  species  have  causal  relations  to  the 
diseases  with  which  mankind  is  afflicted.  This  knowl- 
edge of  the  parasites  was  another  long  step  in  the  direc- 
tion of  scientific  medical  knowledge;  but  the  heights  to 
which  this  knowledge  led  were  not  to  be  scaled,  or  even 
recognized,  until  another  generation  of  workers  had  en- 
tered the  field. 

in 

Meantime,  in  quite  another  field  of  medicine,  events 
were  developing  which  led  presently  to  a  revelation  of 
greater  immediate  importance  to  humanity  than  any 

365 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

other  discovery  that  had  come  in  the  century,  perhaps 
in  any  field  of  science  whatever.  This  was  the  discov- 
ery of  the  pain-dispelling  power  of  the  vapor  of  sul- 
phuric ether,  inhaled  by  a  patient  undergoing  a  surgical 
operation.  This  discovery  come  solely  out  of  America, 
and  it  stands  curiously  isolated,  since  apparently  no 
minds  in  any  other  country  were  trending  towards  it 
even  vaguely.  Davy,  in  England,  had  indeed  originated 
the  method  of  medication  by  inhalation,  and  carried  out 
some  most  interesting  experiments  fifty  years  earlier, 
and  it  was  doubtless  his  experiments  with  nitrous  oxide 
gas  that  gave  the  clew  to  one  of  the  American  investi- 
gators ;  but  this  was  the  sole  contribution  of  preceding 
generations  to  the  subject,  and  since  the  beginning  of 
the  century,  when  Davy  turned  his  attention  to  other 
matters,  no  one  had  made  the  slightest  advance  along 
the  same  line  until  an  American  dentist  renewed  the 
investigation.  Moreover,  there  had  been  nothing-  in 
Davy's  experiments  to  show  that  a  surgical  operation 
might  be  rendered  painless  in  this  way ;  and,  indeed, 
the  surgeons  of  Europe  had  acknowledged  with  one  ac- 
cord that  all  hope  of  finding  a  means  to  secure  this 
most  desirable  end  must  be  utterly  abandoned — that  the 
surgeon's  knife  must  ever  remain  a  synonym  for  slow 
and  indescribable  torture.  By  an  odd  coincidence  it 
chanced  that  Sir  Benjamin  Brodie,  the  acknowledged 
leader  of  English  surgeons,  had  publicly  expressed  this 
as  his  deliberate  though  regretted  opinion  at  a  time 
when  the  quest  which  he  considered  futile  had  already 
led  to  the  most  brilliant  success  in  America,  and  while 
the  announcement  of  the  discovery,  which  then  had  no 
transatlantic  cable  to  convey  it,  was  actually  on  its  way 
to  the  Old  World. 


WILLIAM  T.    G.  MORTON 


CENTURY'S   PROGRESS   IN   SCIENTIFIC   MEDICINE 

The  American  dentist  just  referred  to,  who  was,  with 
one  exception  to  be  noted  presently,  the  first  man  in  the 
world  to  conceive  that  the  administration  of  a  definite 
drug  might  render  a  surgical  operation  painless,  and  to 
give  the  belief  application,  was  Dr.  Horace  Wells,  of 
Hartford,  Connecticut.  The  drug  with  which  he  experi- 
mented was  nitrous  oxide ;  the  operation  which  he  ren- 
dered painless  was  no  more  important  than  the  extrac- 
tion of  a  tooth — yet  it  sufficed  to  mark  a  principle ;  the 
year  of  the  experiment  was  1844. 

The  experiments  of  Dr.  Wells,  however,  though  im- 
portant, were  not  sufficiently  demonstrative  to  bring  the 
matter  prominently  to  the  attention  of  the  medical 
world.  The  drug  with  which  he  experimented  proved 
not  always  reliable,  and  he  himself  seems  ultimately  to 
have  given  the  matter  up,  or  at  least  to  have  relaxed  his 
efforts.  But  meantime  a  friend,  to  whom  he  had  com- 
municated his  belief  and  expectations,  took  the  matter 
up,  and  with  unremitting  zeal  carried  forward  experi- 
ments that  were  destined  to  lead  to  more  tangible  re- 
sults. This  friend  was  another  dentist,  Dr.  W.  T.  G. 
Morton,  of  Boston,  then  a  young  man,  full  of  youthful 
energy  and  enthusiasm.  He  seems  to  have  felt  that  the 
drug  with  which  Wells  had  experimented  was  not  the 
most  practicable  one  for  the  purpose,  and  so  for  several 
months  he  experimented  with  other  allied  drugs,  until 
finally  he  hit  upon  sulphuric  ether,  and  with  this  was 
able  to  make  experiments  upon  animals,  and  then  upon 
patients  in  the  dental  chair,  that  seemed  to  him  abso- 
lutely demonstrative. 

Full  of  eager  enthusiasm,  and  absolutely  confident  of  his 
results,  he  at  once  went  to  Dr.  J.  C.  Warren,  one  of  the 
foremost  surgeons  of  Boston,  and  asked  permission  to 
2  A  369 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

test  his  discovery  decisively  on  one  of  the  patients  at 
the  Boston  Hospital  during  a  severe  operation.  The  re- 
quest was  granted ;  the  test  was  made  on  October  16, 1846, 
in  the  presence  of  several  of  the  foremost  surgeons  of 
the  city  and  of  a  body  of  medical  students.  The  pa- 
tient slept  quietly  while  the  surgeon's  knife  was  plied, 
and  awoke  to  astonished  comprehension  that  the  ordeal 
was  over.  The  impossible,  the  miraculous,  had  been  ac- 
complished. 

Swiftly  as  steam  could  carry  it — slowty  enough  we 
should  think  it  to-da}r — the  news  was  heralded  to  all  the 
world.  It  was  received  in  Europe  with  incredulity, 
which  vanished  before  repeated  experiments.  Surgeons 
were  loath  to  believe  that  ether,  a  drug  that  had  long 
held  a  place  in  the  subordinate  armamentarium  of  the 
physician,  could  accomplish  such  a  miracle.  But  scepti- 
cism vanished  before  the  tests  which  any  surgeon  might 
make,  and  which  surgeons  all  over  the  world  did  make 
within  the  next  few  weeks.  Then  there  came  a  linger- 
ing outcry  from  a  few  surgeons,  notably  some  of  the 
Parisians,  that  the  shock  of  pain  was  beneficial  to  the 
patient,  hence  that  anaesthesia — as  Dr.  Oliver  Wendell 
Holmes  had  christened  the  new  method — was  a  proced- 
ure not  to  be  advised.  Then,  too,  there  came  a  hue- 
and-cry  from  many  a  pulpit  that  pain  was  God-given, 
and  hence,  on  moral  grounds,  to  be  clung  to  rather  than 
renounced.  But  the  outcry  of  the  antediluvians  of  both 
hospital  and  pulpit  quickly  received  its  quietus ;  for  soon 
it  was  clear  that  the  patient  who  did  not  suffer  the 
shock  of  pain  during  an  operation  rallied  better  than  the 
one  who  did  so  suffer,  while  all  humanity  outside  the 
pulpit  cried  shame  to  the  spirit  that  would  doom  man- 
kind to  suffer  needless  agony.  And  so  within  a  few 

" 


CRAWFOKD   W.    LONG 

After  a  crayon  portrait  taken  at  the  time  of  his  discovery  of  the  anaesthetic 
properties  of  sulphuric  ether 


CENTURY'S   PROGRESS   IN   SCIENTIFIC  MEDICINE 

months  after  that  initial  operation  at  the  Boston  Hos- 
pital in  1846,  ether  had  made  good  its  conquest  of  pain 
throughout  the  civilized  world.  Only  by  the  most  ac- 
tive use  of  the  imagination  can  we  of  this  present  day 
realize  the  full  meaning  of  that  victory. 

It  remains  to  be  added  that  in  the  subsequent  bicker- 
ings over  the  discovery — such  bickerings  as  follow  every 
great  advance — two  other  names  came  into  prominent 
notice  as  sharers  in  the  glory  of  the  new  method.  Both 
these  were  Americans— the  one,  Dr.  Charles  T.  Jackson, 
of  Boston ;  the  other,  Dr.  Crawford  W.  Long,  of  Ala- 
bama. As  to  Dr.  Jackson,  it  is  sufficient  to  say  that  he 
seems  to  have  had  some  vague  inkling  of  the  peculiar 
properties  of  ether  before  Morton's  discovery.  He  even 
suggested  the  use  of  this  drug  to  Morton,  not  knowing 
that  Morton  had  already  tried  it ;  but  this  is  the  full 
measure  of  his  association  with  the  discovery.  Hence  it 
is  clear  that  Jackson's  claim  to  equal  share  with  Mor- 
ton in  the  discovery  was  unwarranted,  not  to  say  ab- 
surd. 

Dr.  Long's  association  with  the  matter  was  far  differ- 
ent, and  altogether  honorable.  By  one  of  those  coinci- 
dences so  common  in  the  history  of  discovery,  he  was 
experimenting  with  ether  as  a  pain-destroyer  simulta- 
neously with  Morton,  though  neither  so  much  as  knew 
of  the  existence  of  the  other.  While  a  medical  student 
he  had  once  inhaled  ether  for  the  intoxicant  effects,  as 
other  medical  students  were  wont  to  do,  and  when  par- 
tially under  influence  of  the  drug  he  had  noticed  that  a 
chance  blow  to  his  shins  was  painless.  This  gave  him. 
the  idea  that  ether  might  be  used  in  surgical  operations; 
and  in  subsequent  years,  in  the  course  of  his  practice  in 
a  small  Georgia  town,  he  put  the  idea  into  successful 

373 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

execution.  There  appears  to  be  no  donbt  whatever  that 
he  performed  successful  minor  operations  under  ether 
some  two  or  three  years  before  Morton's  final  demon- 
stration; hence  that  the  merit  of  first  using  the  drug, 
or  indeed  any  drug,  in  this  way  belongs  to  him.  But 
unfortunately  Dr.  Long  did  not  quite  trust  the  evidence 
of  his  own 'experiments.  Just  at  that  time  the  medical 
journals  were  full  of  accounts  of  experiments  in  which 
painless  operations  were  said  to  be  performed  through 
practice  of  hypnotism,  and  Dr.  Long  feared  that  his  own 
success  might  be  due  to  an  incidental  hypnotic  influence 
rather  than  to  the  drug.  Hence  he  delayed  announcing 
his  apparent  discovery  until  he  should  have  opportunity 
for  further  tests— and  opportunities  did  not  come  every 
day  to  the  county  practitioner.  And  while  he  waited, 
Morton  anticipated  him,  and  the  discovery  was  made 
known  to  the  world  without  his  aid.  It  was  a  true  sci- 
entific caution  that  actuated  Dr.  Long  to  this  delay,  but 
the  caution  cost  him  the  credit,  which  might  otherwise 
have  been  his,  of  giving  to  the  world  one  of  the  greatest 
blessings  that  science  has  ever  conferred  upon  hu- 
manity. 

A  few  months  after  the  use  of  ether  became  general, 
the  Scotch  surgeon  Sir  J.  Y.  Simpson  discovered  that 
another  drug,  chloroform,  could  be  administered  with 
similar  effects ;  that  it  would,  indeed,  in  many  cases  pro- 
duce anesthesia  more  advantageously  even  than  ether. 
From  that  day  till  this  surgeons  have  been  more  or  less 
divided  in  opinion  as  to  the  relative  merits  of  the  two 
drugs ;  but  this  fact,  of  course,  has  no  bearing  whatever 
upon  the  merit  of  the  first  discovery  of  the  method  of 
anesthesia.  Even  had  some  other  drug  subsequently 
quite  banished  ether,  the  honor  of  the  discovery  of  the 

374 


CENTURY'S   PROGRESS   IN   SCIENTIFIC   MEDICINE 

beneficent  method  of  anaesthesia  would  have  been  in  no 
wise  invalidated.  And  despite  all  cavillings,  it  is  un- 
equivocally established  that  the  man  who  gave  that 
method  to  the  world  was  William  T.  G.  Morton. 


IV 

This  discovery  of  the  anaesthetic  power  of  drugs  was 
destined  presently,  in  addition  to  its  direct  beneficences, 
to  aid  greatly  in  the  progress  of  scientific  medicine,  by 
facilitating  those  experimental  studies  of  animals  from 
which,  before  the  day  of  anaesthesia,  many  humane 
physicians  were  withheld,  and  which  in  recent  years  have 
led  to  discoveries  of  such  inestimable  value  to  humanity. 
But  for  the  moment  this  possibility  was  quite  overshad- 
owed by  the  direct  benefits  of  anaesthesia,  and  the  long 
strides  that  were  taken  in  scientific  medicine  during  the 
first  fifteen  years  after  Morton's  discovery  were  mainly 
independent  of  such  aid.  These  steps  were  taken,  in- 
deed, in  a  field  that  at  first  glance  might  seem  to  have 
a  very  slight  connection  with  medicine.  Moreover,  the 
chief  worker  in  the  field  was  not  himself  a  physician. 
He  was  a  chemist,  and  the  work  in  which  he  was  now 
engaged  was  the  study  of  alcoholic  fermentation  in  vi- 
nous liquors.  Yet  these  studies  paved  the  way  for  the 
most  important  advances  that  medicine  has  made  in  any 
century  towards  the  plane  of  true  science ;  and  to  this 
man  more  than  to  any  other  single  individual — it  might 
almost  be  said  more  than  to  all  other  individuals — was 
due  this  wonderful  advance.  It  is  almost  superfluous  to 
add  that  the  name  of  this  marvellous  chemist  was  Louis 
Pasteur. 

The  studies  of  fermentation  which  Pasteur  entered 

375 


THE  STORY   OF  NINETEENTH-CENTURY   SCIENCE 

upon  in  1854:  were  aimed  at  the  solution  of  a  contro- 
versy  that  had  been  waging  in  the  scientific  world  with 
varying  degrees  of  activity  for  a  quarter  of  a  century. 
Back  in  the  thirties,  in  the  day  of  the  early  enthusiasm  over 
the  perfected  microscope,  there  had  arisen  a  new  inter- 
est in  the  minute  forms  of  life  which  Leeuwenhoek  and 
some  of  the  other  early  workers  with  the  lens  had  first 
described,  and  which  now  were  shown  to  be  of  almost 
universal  prevalence.  These  minute  organisms  had  been 
studied  more  or  less  by  a  host  of  observers,  but  in  par- 
ticular by  the  Frenchman  Cagniard  Latour  and  the  Ger- 
man, of  cell-theory  fame,  Theodor  Schwann.  These 
men,  working  independently,  had  reached  the  conclu- 
sion, about  1837,  that  the  micro-organisms  play  a  vastly 
more  important  role  in  the  economy  of  nature  than  any 
one  previously  had  supposed.  They  held,  for  example, 
that  the  minute  specks  which  largely  make  up  the  sub- 
stance of  yeast  are  living  vegetable  organisms,  and  that 
the  growth  of  these  organisms  is  the  cause  of  the  im- 
portant and  familiar  process  of  fermentation.  They 
even  came  to  hold,  at  least  tentatively,  the  opinion  that 
the  somewhat  similar  micro-organisms  to  be  found  in  all 
putrefying  matter,  animal  or  vegetable,  had  a  causal  re- 
lation to  the  process  of  putrefaction. 

This  view,  particularly  as  to  the  nature  of  putrefac- 
tion, was  expressed  even  more  outspokenly  a  little  later 
by  the  French  botanist  Turpin.  Yiews  so  supported 
naturally  gained  a  following;  it  was  equally  natural 
that  so  radical  an  innovation  should  be  antagonized.  In 
this  case  it  chanced  that  one  of  the  most  dominating 
scientific  minds  of  the  time,  that  of  Liebig,  took  a  firm 
and  aggressive  stand  against  the  new  doctrine.  In  1839 
he  promulgated  his  famous  doctrine  of  fermentation,  in 

376 


THEODOll   SCHWANN 


CENTURY'S   PROGRESS   IN   SCIENTIFIC   MEDICINE 

which  he  stood  out  firmly  against  any  "  vitalistic  "  ex- 
planation, of  the  phenomena,  alleging  that  the  presence 
of  micro-organisms  in  fermenting  and  putrefying  sub- 
stances was  merely  incidental,  and  in  no  sense  causal. 
This  opinion  of  the  great  German  chemist  was  in  a 
measure  substantiated  by  experiments  of  his  compatriot 
Helmholtz,  whose  earlier  experiments  confirmed,  but 
later  ones  contradicted,  the  observations  of  Schwann, 
and  this  combined  authority  gave  the  vitalistic  concep- 
tion a  blow  from  which  it  had  not  rallied  at  the  time 
when  Pasteur  entered  the  field.  Indeed,  it  was  current- 
ly regarded  as  settled  that  the  early  students  of  the 
subject  had  vastly  overestimated  the  importance  of  mi- 
cro-organisms. 

And  so  it  came  as  anew  revelation  to  the  generality  of 
scientists  of  the  time,  when,  in  1857  and  the  succeeding 
half-decade,  Pasteur  published  the  results  of  his  re- 
searches, in  which  the  question  had  been  put  to  a  series 
of  altogether  new  tests,  and  brought  to  unequivocal 
demonstration. 

He  proved  that  the  micro-organisms  do  all  that  his ] 
most  imaginative  predecessors  had  suspected,  and  more. 
Without  them,  he  proved,  there  would  be  no  fermenta- 
tion, no  putrefaction — no  decay  of  any  tissues,  except  by 
the  slow  process  of  oxidation.  It  is  the  microscopic 
yeast  plant  which,  by  seizing  on  certain  atoms  of  the 
molecule,  liberates  the  remaining  atoms  in  the  form  of 
carbonic  acid  and  alcohol,  thus  effecting  fermentation ; 
it  is  another  microscopic  plant — a  bacterium,  as  Devaine 
had  christened  it — which  in  a  similar  way  effects  the 
destruction  of  organic  molecules,  producing  the  condi- 
tion which  we  call  putrefaction.  Pasteur  showed,  to 
the  amazement  of  biologists,  that  there  are  certain  forms 

379   . 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

of  these  bacteria  which  secure  the  oxygen  which  all  or- 
ganic life  requires,  not  from  the  air,  but  by  breaking  up 
unstable  molecules  in  which  oxygen  is  combined ;  that 
putrefaction,  in  short,  has  its  foundation  in  the  activities 
of  these  so-called  anaerobic  bacteria. 

In  a  word,  Pasteur  showed  that  all  the  many  familiar 
processes  of  the  decay  of  organic  tissues  are,  in  effect, 
forms  of  fermentation,  and  would  not  take  place  at  all 
except  for  the  presence  of  the  living  micro-organisms. 
A  piece  of  meat,  for  example,  suspended  in  an  atmos- 
phere free  from  germs,  will  dry  up  gradually,  without 
the  slightest  sign  of  putrefaction,  regardless  of  the  tem- 
perature or  other  conditions  to  which  it  may  have  been 
£_subjected. 

There  was  nothing  in  these  studies  bearing  directly 
upon  the  question  of  animal  diseases,  yet  before  they 
were  finished  they  had  stimulated  progress  in  more  than 
one  field  of  pathology.  At  the  very  outset  they  sufficed 
to  start  afresh  the  inquiry  as  to  the  role  played  by  mi- 
cro-organisms in  disease.  In  particular,  they  led  the 
French  physician  Devaine  to  return  to  some  interrupted 
studies  which  he  had  made  ten  years  before,  in  reference 
to  the  animal  disease  called  anthrax,  or  splenic  fever,  a 
disease  that  cost  the  farmers  of  Europe  millions  of 
francs  annually  through  loss  of  sheep  and  cattle.  In 
1850,  Devaine  had  seen  multitudes  of  bacteria  in  the 
blood  of  animals  who  had  died  of  anthrax,  but  he  did 
not  at  that  time  think  of  them  as  having  a  causal  rela- 
tion to  the  disease.  Now,  however,  in  1863,  stimulated 
by  Pasteur's  new  revelations  regarding  the  power  of 
bacteria,  he  returned  to  the  subject,  and  soon  became 
convinced,  through  experiments  by  means  of  inocula- 
tion, that  the  microscopic  organisms  he  had  discovered 

380 


CENTURY'S   PROGRESS   IN   SCIENTIFIC  MEDICINE 

\vere  the  veritable  and  the  sole  cause  of  the  infectious 
disease  anthrax. 

The  publication  of  this  belief  in  1863  aroused  a  furor 
of  controversy.  That  a  microscopic  vegetable  could 
cause  a  virulent  systemic  disease  was  an  idea  altogether 
too  startling  to  be  accepted  in  a  day,  and  the  generality 
of  biologists  and  physicians  demanded  more  convincing 
proofs  than  Devaine  as  yet  was  able  to  offer. 

Naturally  a  host  of  other  investigators  all  over  the 
world  entered  the  field.  Foremost  among  these  was  the 
German  Dr.  Robert  Koch,  who  soon  corroborated  all 
that  Devaine  had  observed,  and  carried  the  experiments 
further  in  the  direction  of  the  cultivation  of  successive 
generations  of  the  bacteria  in  artificial  media,  inocula- 
tions being  made  from  such  pure  cultures  of  the  eighth 
generation,  with  the  astonishing  result  that  animals  thus 
inoculated  at  once  succumbed  to  the  disease. 

Such  experiments  seem  demonstrative,  yet  the  world 
was  unconvinced,  and  in  1876,  while  the  controversy 
was  still  at  its  height,  Pasteur  was  prevailed  upon  to 
take  the  matter  in  hand.  The  great  chemist  was  be- 
coming more  and  more  exclusively  a  biologist  as  the 
years  passed,  and  in  recent  years  his  famous  studies  of 
the  silk- worm  diseases,  which  he  proved  due  to  bacterial  in- 
fection, and  of  the  question  of  spontaneous  generation,  had 
given  him  unequalled  resources  in  microscopical  technique. 
And  so  when,  with  the  aid  of  his  laboratory  associates 
Dnclaux  and  Chamberland  and  Roux,  he  took  up  the 
mooted  anthrax  question,  the  scientific  world  awaited 
the  issue  with  bated  breath.  And  when,  in  1877,  Pas- 
teur was  ready  to  report  on  his  studies  of  anthrax,  he 
came  forward  with  such  a  wealth  of  demonstrative  ex- 
periments— experiments  the  rigid  accuracy  of  which  no 

381 


THE   STORY   OF  NINETEENTH-CENTURY   SCIENCE 

one  would  for  a  moment  think  of  questioning — going  to 
prove  the  bacterial  origin  of  anthrax,  that  scepticism 
was  at  last  quieted  for  all  time  to  come. 

Henceforth  no  one  could  doubt  that  the  contagious 
disease  anthrax  is  due  exclusively  to  the  introduction 
into  an  animal's  system  of  a  specific  germ — a  micro- 
scopic plant  —  which  develops  there.  And  no  logical 
mind  could  have  a  reasonable  doubt  that  what  is  proved 
true  of  one  infectious  disease  would  some  day  be  proved 
true  also  of  other,  perhaps  of  all,  forms  of  infectious 
maladies. 

Hitherto  the  cause  of  contagion,  b\r  which  certain 
maladies  spread  from  individual  to  individual,  had  been 
a  total  mystery,  quite  unillumined  by 'the  vague  terms 
"  miasm,"  "humor,"  "virus,"  and  the  like  cloaks  of  ig- 
norance. Here  and  there  a  prophet  of  science,  as  Sch  wann 
and  Henle,  had  guessed  the  secret;  but  guessing,  in  sci- 
ence, is  far  enough  from  knowing.  Now,  for  the  first 
time,  the  world  knew,  and  medicine  had  taken  another 
gigantic  stride  towards  the  heights  of  exact  science. 


Meantime  in  a  different,  though  allied,  field  of  medi- 
cine there  had  been  a  complementary  growth  that  led 
to  immediate  results  of  even  more  practical  importance. 
I  mean  the  theory  and  practice  of  antisepsis  in  surgery. 
This  advance,  like  the  other,  came  as  a  direct  outgrowth 
of  Pasteur's  fermentation  studies  of  alcoholic  beverages, 
though  not  at  the  hands  of  Pasteur  himself.  Struck  by 
the  boundless  implications  of  Pasteur's  revelations  re- 
garding the  bacteria,  Dr.  Joseph  Lister  (the  present 
Lord  Lister),  then  of  Glasgow,  set  about  as  early  as 

382 


SIR  JOSEPH   LISTER 


CENTURY'S    PROGRESS   IN   SCIENTIFIC   MEDICINE 

1860  to  make  a  wonderful  application  of  these  ideas.  If 
putrefaction  is  always  due  to  bacterial  development,  he 
argued,  this  must  apply  as  well  to  living  as  to  dead  tis- 
sues ;  hence  the  putrefactive  changes  which  -occur  in 
wounds  and  after  operations  on  the  human  subject,  from 
which  blood-poisoning  so  often  follows,  might  be  abso- 
lutely prevented  if  the  injured  surfaces  could  be  kept 
free  from  access  of  the  germs  of  decay. 

In  the  hope  of  accomplishing  this  result,  Lister  began 
experimenting  with  drugs  that  might  kill  the  bacteria 
without  injury  to  the  patient,  and  with  means  to  pre- 
vent further  access  of  germs  once  a  wound  was  freed 
from  them.  How  well  he  succeeded,  all  the  world 
knows ;  how  bitterly  he  was  antagonized  for  about  a 
score  of  years,  most  of  the  world  has  already  forgotten. 
As  early  as  1867,  Lister  was  able  to  publish  results 
pointing  towards  success  in  his  great  project ;  yet  so  in- 
credulous were  surgeons  in  general  that  even  some  years 
later  the  leading  surgeons  across  the  Channel  had  not 
so  much  as  heard  of  his  efforts.  In  1870  the  soldiers  of 
Paris  died,  as  of  old,  of  hospital  gangrene;  and  when  in 
1871  the  French  surgeon  Alphonse  Guerin,  stimulated 
by  Pasteur's  studies,  conceived  the  idea  of  dressing 
wounds  with  cotton  in  the  hope  of  keeping  germs  from 
entering  them,  he  was  quite  unaware  that  a  British  con- 
temporary had  preceded  him  by  a  full  decade  in  this  ef- 
fort at  prevention,  and  had  made  long  strides  towards 
complete  success.  Lister's  priority,  however,  and  the 
superiority  of  his  method,  were  freely  admitted  by  the 
French  Academy  of  Science,  which  in  1881  officially 
crowned  his  achievement,  as  the  Eoyal  Society  of  Lon- 
don had  done  the  year  before. 

By  this  time,  to  be  sure,  as  everybody  knows,  Lister's 
SB  385 


THE   STOKY   OF   NINETEENTH-CENTURY    SCIENCE 

new  methods  had  made  their  way  everywhere,  revolu- 
tionizing the  practice  of  surgery,  and  practically  banish- 
ing from  the  earth  maladies  that  hitherto  had  been  the 
terror  of  the  surgeon  and  the  opprobrium  of  his  art. 
And  these  bedside  studies,  conducted  in  the  end  by 
thousands  of  men  who  had  no  knowledge  of  microscopy, 
had  a  large  share  in  establishing  the  general  belief  in 
the  causal  relation  that  micro-organisms  bear  to  disease, 
which  by  about  the  year  1880  had  taken  possession  of 
the  medical  world.  But  they  did  more ;  they  brought 
into  equal  prominence  the  idea  that,  the  cause  of  a  dis- 
eased condition  being  known,  it  may  be  possible  as 
never  before  to  grapple  with  and  eradicate  that  condi- 
tion. 

The  controversy  over  spontaneous  generation,  which, 
thanks  to  Pasteur  and  Tyndall,  had  just  been  brought 
to  a  termination,  made  it  clear  that  no  bacterium  need 
be  feared  where  an  antecedent  bacterium  had  not  found 
lodgment;  Listerism  in  surgery  had  now  shown  how 
much  might  be  accomplished  towards  preventing  the 
access  of  germs  to  abraded  surfaces  of  the  body,  and 
destroying  those  that  already  had  found  lodgment 
there.  As  yet,  however,  there  was  no  inkling  of  a  way 
in  which  a  corresponding  onslaught  might  be  made  upon 
those  other  germs  which  find  their  way  into  the  animal 
organism  by  way  of  the  mouth  and  the  nostrils,  and  which, 
as  was  now  clear,  are  the  cause  of  those  contagious  diseases 
which,  first  and  last,  claim  so  large  a  proportion  of  man- 
kind for  their  victims.  How  such  means  might  be 
found  now  became  the  anxious  thought  of  every  im- 
aginative physician,  of  every  working  micro- biologist. 

As  it  happened,  the  world  was  not  kept  long  in  sus- 
pense. Almost  before  the  proposition  had  taken  shape 


CENTURY'S   PROGRESS   IN  SCIENTIFIC   MEDICINE 

in  the  minds  of  the  other  leaders,  Pasteur  had  found  a 
solution.  Guided  by  the  empirical  success  of  Jenner, 
he,  like  many  others,  had  long  practised  inoculation  ex- 
periments, and  on  the  9th  of  February,  1880,  he  an- 
nounced to  the  French  Academy  of  Science  that  he  had 
found  a  method  of  so  reducing  the  virulence  of  a  disease 
germ  that,  when  introduced  into  the  system  of  a  sus- 
ceptible animal,  it  produced  only  a  mild  form  of  the  dis- 
ease, which,  however,  sufficed  to  protect  against  the 
usual  virulent  form  exactly  as  vaccinia  protects  against 
small-pox.  The  particular  disease  experimented  with 
was  that  infectious  malady  of  poultry  known  familiarly 
as  "chicken  cholera."  In  October  of  the  same  year 
Pasteur  announced  the  method  by  which  this  "attenu- 
ation of  the  virus,"  as  he  termed  it,  had  been  brought 
about — by  cultivation  of  the  disease  germs  in  artificial 
media,  exposed  to  the  air;  and  he  did  not  hesitate  to 
assert  his  belief  that  the  method  would  prove  "  suscepti- 
ble of  generalization  " — that  is  to  say,  of  application  to 
other  diseases  than  the  particular  one  in  question. 

Within  a  few  months  he  made  good  this  prophecy, 
for  in  February,  1881,  he  announced  to  the  Academy 
that,  with  the  aid,  as  before,  of  his  associates  MM. 
Chamberland  and  lioux,  he  had  produced  an  attenuated 
virus  of  the  anthrax  microbe,  by  the  use  of  which  he 
could  protect  sheep,  and  presumably  cattle,  against  that 
fatal  malady. 

This  announcement  was  immediately  challenged  in 
a  way  that  brought  it  to  the  attention  of  the  entire 
world.  The  president  of  an  agricultural  society,  real- 
izing the  enormous  importance  of  the  subject,  proposed 
to  Pasteur  that  his  alleged  discovery  should  be  submit- 
ted to  a  decisive  public  test.  He  proposed  to  furnish  a 

387 


THE   STORY   OF  NINETEENTH-CENTURY  SCIENCE 

drove  of  fifty  sheep,  half  of  which  were  to  be  inoculated 
with  the  attenuated  virus  by  Pasteur.  Subsequently  all 
the  sheep  were  to  be  inoculated  with  virulent  virus,  all 
being  kept  together  in  one  pen,  under  precisely  the  same 
conditions.  The  "protected''  sheep  were  to  remain 
healthy;  the  unprotected  ones  to  die  of  anthrax;  so 
read  the  terms  of  the  proposition.  Pasteur  accepted 
the  challenge ;  he  even  permitted  a  change  in  the  pro- 
gramme by  which  two  goats  were  substituted  for  two 
of  the  sheep,  and  ten  cattle  added  ;  stipulating,  however, 
that  since  his  experiments  had  not  yet  been  extended  to 
cattle,  these  should  not  be  regarded  as  falling  rigidly 
within  the  terras  of  the  test. 

It  was  a  test  to  try  the  soul  of  any  man,  for  all  the 
world  looked  on  askance,  prepared  to  deride  the  maker 
of  so  preposterous  a  claim  as  soon  as  his  claim  should  be 
proved  baseless.  Not  even  the  fame  of  Pasteur  could 
make  the  public  at  large,  lay  or  scientific,  believe  in  the 
possibility  of  what  he  proposed  to  accomplish.  There 
was  time  for  all  the  world  to  be  informed  of  the  proced- 
ure, for  the  first  "preventive"  inoculation,  or  vaccina- 
tion, as  Pasteur  termed  it,  was  made  on  the  5th  of  May, 
the  second  on  the  17th  ;  and  another  interval  of  two 
weeks  must  elapse  before  the  final  inoculations  with  the 
unattenuated  virus.  Twenty -four  sheep,  one  goat,  and 
five  cattle  were  submitted  to  the  preliminary  vaccina- 
tions. Then,  on  the  31st  of  May,  all  sixty  of  the  ani- 
mals were  inoculated,  a  protected  and  an  unprotected 
one  alternately,  with  an  extremely  virulent  culture  of 
anthrax  microbes  that  had  been  in  Pasteur's  laboratory 
since  1877.  This  accomplished,  the  animals  were  left 
together  in  one  enclosure,  to  await  the  issue. 

O 

Two  days  later,  the  2d  of  June,  at  the  appointed  hour 

388 


CENTURY'S   PROGRESS   IN   SCIENTIFIC   MEDICINE 

of  rendezvous,  a  vast  crowd,  composed  of  veterinary  sur- 
geons, newspaper  correspondents,  and  farmers  from  far 
and  near,  gathered  to  witness  the  closing  scenes  of  this 
scientific  tourney.  What  they  saw  was  one  of  the  most 
dramatic  scenes  in  the  history  of  peaceful  science — a 
scene  which,  as  Pasteur  declared  afterwards,  "  amazed 
the  assembly."  Scattered  about  the  enclosure,  dead, 
dying,  or  manifestly  sick  unto  death,  lay  the  unprotected 
animals,  one  and  all;  while  each  and  every  "protected" 
animal  stalked  unconcernedly  about  with  every  appear- 
ance of  perfect  health.  Twenty  of  the  sheep  and  the 
one  goat  were  already  dead ;  two  other  sheep  expired 
under  the  eyes  of  the  spectators ;  the  remaining  victims 
lingered  but  a  few  hours  longer.  Thus  in  a  manner 
theatrical  enough,  not  to  say  tragic,  was  proclaimed  the 
unequivocal  victory  of  science.  Naturally  enough,  the 
unbelievers  struck  their  colors  and  surrendered  without 
terras  ;  the  principle  of  protective  vaccination,  with  a 
virus  experimentally  prepared  in  the  laboratory,  was  es- 
tablished beyond  the  reach  of  controversy. 

That  memorable  scientific  battle  marked  the  begin- 
ning of  a  new  era  in  medicine.  It  was  a  foregone  con- 
clusion that  the  principle  thus  established  would  be  still 
further  generalized ;  that  it  would  be  applied  to  human 
maladies;  that,  in  all  probability,  it  would  grapple  suc- 
cessfully, sooner  or  later,  with  many  infectious  diseases. 
That  expectation  has  advanced  rapidly  towards  realiza- 
tion. Pasteur  himself  made  the  application  to  the  hu- 
man subject  in  the  disease  hydrophobia,  in  1885,  since 
which  time  that  hitherto  most  fatal  of  maladies  has 
largely  lost  its  terrors.  Thousands  of  persons,  bitten 
by  mad  dogs,  have  been  snatched  from  the  fatal  conse- 
quences of  that  mishap  by  this  method,  at  the  Pasteur 

'889     • 


THE   STORY   OF   NINETEENTU-CENTURY  SCIENCE 

Institute  in  Paris,  and  at  the  similar  institutes,  built  on 
the  model  of  this  parent  one,  that  have  been  established 
all  over  the  world,  in  regions  as  widely  separated  as 
New  York  and  Nha-Trang. 


VI 

In  the  production  of  the  rabies  vaccine  Pasteur  and 
his  associates  developed  a  method  of  attenuation  of  a 
virus  quite  different  from  that  which  had  been  employed 
in  the  case  of  the  vaccines  of  chicken  cholera  and  of  an- 
thrax. The  rabies  virus  was  inoculated  into  the  system 
of  guinea-pigs  or  rabbits,  and,  in  effect,  cultivated  in  the 
systems  of  these  animals.  The  spinal  cord  of  these  in- 
fected animals  was  found  to  be  rich  in  the  virus,  which 
rapidly  became  attenuated  when  the  cord  was  dried  in 
the  air.  The  preventive  virus,  of  varying  strengths,  was 
made  by  maceration  of  these  cords  at  varying  stages  of 
desiccation.  This  cultivation  of  a  virus  within  the  ani- 
mal organism,  suggested,  no  doubt,  by  the  familiar  J"en- 
nerian  method  of  securing  small-pox  vaccine,  was  at  the 
same  time  a  step  in  the  direction  of  a  new  therapeutic 
procedure  which  was  destined  presently  to  become  of 
all-absorbing  importance — the  method,  namely,  of  so- 
called  serum-therapy,  or  the  treatment  of  a  disease  with 
the  blood  serum  of  an  animal  that  has  been  subjected  to 
protective  inoculation  against  that  disease. 

The  possibility  of  such  a  method  was  suggested  by 
the  familiar  observation,  made  by  Pasteur  and  numerous 
other  workers,  that  animals  of  different  species  differ 
widely  in  their  susceptibility  to  various  maladies ;  and 
that  the  virus  of  a  given  disease  may  become  more  and 
more  virulent  when  passed  through  the  systems  of  suc- 

390 


CENTURY'S   PROGRESS   IN    SCIENTIFIC   MEDICINE 

cessive  individuals  of  one  species,  and,  contrariwise,  less 
and  less  virulent  when  passed  through  the  systems  of 
successive  individuals  of  another  species.  These  facts 


LOUIS  PASTEUR 


suggested  the  theory  that  the  blood  of  resistant  animals 
might  contain  something  directly  antagonistic  to  the 
virus,  and  the  hope  that  this  something  might  be  trans- 
ferred with  curative  effect  to  the  blood  of  an  infected 
susceptible  animal.  Numerous  experimenters  all  over 

391 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

the  world  made  investigations  along  the  line  of  this  al- 
luring possibility,  the  leaders  perhaps  being  Drs.  Behring 
and  Kitasato,  closely  followed  by  Dr.  Roux  and  his  as- 
sociates of  the  Pasteur  Institute  of  Paris.  Definite  re- 
sults were  announced  by  Behring  in  1892  regarding  two 
important  diseases  —  tetanus  and  diphtheria  —  but  the 
method  did  not  come  into  general  notice  until  1894, 
when  Dr.  Roux  read  an  epoch-marking  paper  on  the  sub- 
ject at  the  Congress  of  Hygiene  at  Buda-Pesth. 

In  this  paper,  Dr.  Roux,  after  adverting  to  the  labors 
of  Behring,  Ehrlich,  Boer,  Kossel,  and  Wasserman,  de- 
scribed in  detail  the  methods  that  had  been  developed 
at  the  Pasteur  Institute  for  the  development  of  the  cura- 
tive serum,  to  which  Behring  had  given  the  since  familiar 
name  antitoxine.  The  method  consists,  first,  of  the  cul- 
tivation, for  some  months,  of  the  diphtheria  bacillus 
(called  the  Klebs-Loeffler  bacillus,  in  honor  of  its  dis- 
coverers) in  an  artificial  bouillon,  for  the  development 
of  a  powerful  toxine  capable  of  giving  the  disease  in  a 
virulent  form. 

This  toxine,  after  certain  details  of  mechanical  treat- 
ment, is  injected  in  small  but  increasing  doses  into  the 
system  of  an  animal,  care  being  taken  to  graduate  the 
amount  so  that  the  animal  does  not  succumb  to  the 
disease.  After  a  certain  course  of  this  treatment  it  is 
found  that  a  portion  of  blood  serum  of  the  animal  so 
treated  will  act  in  a  curative  way  if  injected  into  the 
blood  of  another  animal,  or  a  human  patient,  suffering 
with  diphtheria.  In  other  words,  according  to  theory, 
an  antitoxine  has  been  developed  in  the  system  of 
the  animal  subjected  to  the  progressive  inoculations 
of  the  diphtheria  toxine.  In  Dr.  Roux's  experience 
the  animal  best  suited  for  the  purpose  is  the  horse, 


CENTURY'S   PROGRESS   IN   SCIENTIFIC    MEDICINE 

though  almost  any  of  the  domesticated  animals  will 
serve  the  purpose. 

But  Dr.  Roux's  paper  did  not  stop  with  the  description 
of  laboratory  methods.  It  told  also  of  the  practical  ap- 
plication of  the  serum  to  the  treatment  of  numerous  cases 
of  diphtheria  in  the  hospitals  of  Paris — applications  that 
had  met  with  a  gratifying  measure  of  success.  He  made 
it  clear  that  a  means  had  been  found  of  coping  success- 
fully with  what  had  been  one  of  the  most  virulent  and 
intractable  of  the  diseases  of  childhood.  Hence  it  was 
not  strange  that  his  paper  made  a  sensation  in  all  circles, 
medical  and  lay  alike. 

Physicians  from  all  over  the  world  flocked  to  Paris  to 
learn  the  details  of  the  open  secret,  and  within  a  few 
months  the  new  serum-therapy  had  an  acknowledged 
standing  with  the  medical  profession  everywhere.  What 
it  had  accomplished  was  regarded  as  but  an  earnest  of 
what  the  new  method  might  accomplish  presently  when 
applied  to  the  other  infectious  diseases. 

Efforts  at  such  applications  were  immediately  begun 
in  numberless  directions — had,  indeed,  been  under  way 
in  many  a  laboratory  for  some  years  before.  It  is  too 
early  yet  to  speak  of  the  results  in  detail.  But  enough 
has  been  done  to  show  that  this  method  also  is  suscep- 
tible of  the  widest  generalization.  It  is  not  easy  at  the 
present  stage  to  sift  that  which  is  tentative  from  that 
which  will  be  permanent ;  but  so  great  an  authority  as 
Behring  does  not  hesitate  to  affirm  that  to-day  we  pos- 
sess, in  addition  to  the  diphtheria  antitoxine,  equally 
specific  antitoxines  of  tetanus,  cholera,  typhus -fever, 
pneumonia,  and  tuberculosis — a  set  of  diseases  which  in 
the  aggregate  account  for  a  startling  proportion  of  the 
general  death-rate.  Then  it  is  known  that  Dr.  Yersin, 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

with  the  collaboration  of  his  former  colleagues  of  the 
Pasteur  Institute,  has  developed,  and  has  used  with  sue* 
cess,  an  antitoxine  from  the  microbe  of  the  plague  which 
recently  ravaged  China. 

Dr.  Calmette,  another  graduate  of  the  Pasteur  Insti- 
tute, has  extended  the  range  of  the  serum -therapy  to 
include  the  prevention  and  treatment  of  poisoning  by 
venoms,  and  has  developed  an  antitoxine  that  has  al- 
ready given  immunity  from  the  lethal  effects  of  snake 
bites  to  thousands  of  persons  in  India  and  Australia. 

Just  how  much  of  present  promise  is  tentative ;  just 
what  are  the  limits  of  the  methods — these  are  questions 
for  the  future  to  decide.  But,  in  any  event,  there  seems 
little  question  that  the  serum  treatment  will  stand  as  the 
culminating  achievement  in  therapeutics  of  our  century. 
It  is  the  logical  outgrowth  of  those  experimental  studies 
with  the  microscope  begun  by  our  predecessors  of  the 
thirties,  and  it  represents  the  present  culmination  of  the 
rigidly  experimental  method  which  has  brought  medi- 
cine from  a  level  of  fanciful  empiricism  to  the  plane  of 
a  rational  experimental  science. 


CHAPTER   XII 

THE    CENTURY'S    PROGRESS    IN    EXPERIMENTAL'  PSY- 
CHOLOGY 

I 

A  LITTLE  over  a  hundred  years  ago  a  reform  move- 
ment was  afoot  in  the  world  in  the  interests  of  the  in- 
sane. As  was  fitting,  the  movement  showed  itself  first 
in  America,  where  these  unfortunates  were  humanely 
cared  for  at  a  time  when  their  treatment  elsewhere  was 
worse  than  brutal,  but  England  and  France  quickly  fell 
into  line.  The  leader  on  this  side  of  the  water  was  the 
famous  Philadelphian,  Dr.  Benjamin  Rush,  "  the  Syden- 
ham  of  America  "  ;  in  England,  Dr.  William  Tuke  inau- 
gurated the  movement;  and  in  France,  Dr.  Philippe 
Pinel,  single-handed,  led  the  way.  Moved  by  a  com- 
mon spirit,  though  acting  quite  independently,  these 
men  raised  a  revolt  against  the  traditional  custom 
which,  spurning  the  insane  as  demon-haunted  outcasts, 
had  condemned  these  unfortunates  to  dungeons,  chains, 
and  the  lash.  Hitherto  few  people  had  thought  it  other 
than  the  natural  course  of  events  that  the  " maniac" 
should  be  thrust  into  a  dungeon,  and  perhaps  chained 
to  the  wall  with  the  aid  of  an  iron  band  riveted  per- 
manently about  his  neck  or  waist.  Many  an  unfortu- 
nate, thus  manacled,  was  held  to  the  narrow  limits  of 
his  chain  for  years  together  in  a  cell  to  which  full  day- 
light never  penetrated  ;  sometimes — iron  being  expen- 

390 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

sive — the  chain  was  so  short  that  the  wretched  victim 
could  not  rise  to  the  upright  posture,  or  even  shift  his 
position  upon  his  squalid  pallet  of  straw. 

In  America,  indeed,  there  being  no  Middle  Age  prece- 
dents to  crystallize  into  established  customs,  the  treat- 
ment accorded  the  insane  had  seldom  or  never  sunk  to 
this  level.  Partly  for  this  reason,  perhaps,  the  work  of 
Dr.  Rush,  at  the  Philadelphia  Hospital,  in  1784,  by 
means  of  which  the  insane  came  to  be  humanely  treat- 
ed, even  to  the  extent  of  banishing  the  lash,  has  been 
but  little  noted,  while  the  work  of  the  European  lead- 
ers, though  belonging  to  later  decades,  has  been  made 
famous.  And  perhaps  this  is  not  as  unjust  as  it  seems, 
for  the  step  which  Rush  took,  from  relatively  bad  to 
good,  was  a  far  easier  one  to  take  than  the  leap  from 
atrocities  to  good  treatment  which  the  European  re- 
formers were  obliged  to  compass.  In  Paris,  for  exam- 
ple, Pinel  was  obliged  to  ask  permission  of  the  authori- 
ties even  to  make  the  attempt  at  liberating  the  insane 
from  their  chains,  and  notwithstanding  his  recognized 
position  as  a  leader  of  science,  he  gained  but  grudging 
assent,  and  was  regarded  as  being  himself  little  better 
than  a  lunatic  for  making  so  manifestly  unwise  and 
hopeless  an  attempt.  Once  the  attempt  had  been  made, 
however,  and  carried  to  a  successful  issue,  the  amelio- 
ration wrought  in  the  condition  of  the  insane  was  so 
patent  that  the  fame  of  Pinel's  work  at  the  Bicetre  and 
the  Salpetriere  went  abroad  apace.  It  required,  indeed, 
many  years  to  complete  it  in  Paris,  and  a  lifetime  of 
effort  on  the  part  of  Pinel's  pupil  Esquirol  and  others 
to  extend  the  reform  to  the  provinces ;  but  the  epochal 
turning-point  had  been  reached  with  Pinel's  labors  of 
the  closing  years  of  the  eighteenth  century. 

396 


r^ 

UN: 

J 
Of 


PROGRESS   IN   EXPERIMENTAL  PSYCHOLOGY 

The  significance  of  this  wise  and  humane  reform,  in 
the  present  connection,  is  the  fact  that  these  studies  of  the 
insane  gave  emphasis  to  the  novel  idea,  which  by-and-by 
became  accepted  as  beyond  question,  that  "  demoniacal 
possession  "  is  in  reality  no  more  than  the  outward  ex- 
pression of  a  diseased  condition  of  the  brain.  This  real- 
ization made  it  clear,  as  never  before,  how  intimately 
the  mind  and  the  body  are  linked  one  to  the  other.  And 
so  it  chanced  that  in  striking  the  shackles  from  the  in- 
sane, Pinel  and  his  confreres  struck  a  blow  also,  un- 
wittingly, at  time  -  honored  philosophical  traditions. 
The  liberation  of  the  insane  from  their  dungeons  was 
an  augury  of  the  liberation  of  psychology  from  the 
musty  recesses  of  metaphysics.  Hitherto  psychology, 
in  so  far  as  it  existed  at  all,  was  but  the  subjective 
study  of  individual  minds;  in  future  it  must  become 
objective  as  well,  taking  into  account  also  the  relations 
which  the  mind  bears  to  the  body,  and  in  particular  to 
the  brain  and  nervous  system. 

The  necessity  for  this  collocation  was  advocated  quite 
as  earnestly,  and  even  more  directly,  by  another  worker 
of  this  period,  whose  studies  were  allied  to  those  of 
alienists,  and  who,  even  more  actively  than  they,  focal- 
ized his  attention  upon  the  brain  and  its  functions.  This 
earliest  of  specialists  in  brain  studies  was  a  German  by 
birth,  but  Parisian  by  adoption,  Dr.  Franz  Joseph  Gall, 
originator  of  the  since  notorious  system  of  phrenology. 
The  merited  disrepute  into  which  this  system  has  fallen 
through  the  expositions  of  peripatetic  charlatans  should 
not  make  us  forget  that  Dr.  Gall  himself  was  appar- 
ently a  highly  educated  physician,  a  careful  student 
of  the  brain  and  mind  according  to  the  best  light 
of  his  time,  and,  withal,  an  earnest  and  honest  be- 

399 


THE  STOHY   OF  NINETEENTH -CENTURY   SCIENCE 

liever  in  the  validity  of  the  system  he  had  originated. 
The  system  itself,  taken  as  a  whole,  was  hopelessly 
faulty,  yet  it  was  not  without  its  latent  germ  of  truth, 
as  later  studies  were  to  show.  How  firmly  its  author 
himself  believed  in  it  is  evidenced  by  the  paper  which 
he  contributed  to  the  French  Academy  of  Science  in 
1808.  The  paper  itself  was  referred  to  a  committee  of 
which  Pinel  and  Cuvier  were  members.  The  verdict  of 
this  committee  was  adverse,  and  justly  so;  yet  the  sys- 
tem condemned  had  at  least  one  merit  which  its  de- 
tractors failed  to  realize.  It  popularized  the  conception 
that  the  brain  is  the  organ  of  mind.  Moreover,  by 
its  insistence  it  rallied  about  it  a  band  of  scientific  sup- 
porters, chief  of  whom  was  Dr.  Kaspar  Spurzheim,  a 
man  of  no  mean  abilities,  who  became  the  propagandist 
of  phrenology  in  England  and  in  America.  Of  course 
such  advocacy  and  popularity  stimulated  opposition  as 
well,  and  out  of  the  disputations  thus  arising  there  grew 
presently  a  general  interest  in  the  brain  as  the  organ  of 
mind,  quite  aside  from  any  preconceptions  whatever  as 
to  the  doctrines  of  Gall  and  Spurzheim. 

Prominent  among  the  unprejudiced  class  of  workers 
who  now  appeared  was  the  brilliant  young  Frenchman, 
Louis  Antoine  Desmoulins,  who  studied  first  under  the 
tutorage  of  the  famous  Magendie,  and  published  jointly 
with  him  a  classical  work  on  the  nervous  system  of  ver- 
tebrates in  1825.  Desmoulins  made  at  least  one  discov- 
ery of  epochal  importance.  He  observed  that  the  brains 
of  persons  dying  in  old  age  were  lighter  than  the  aver- 
age, and  gave  visible  evidence  of  atrophy,  and  he  rea- 
soned that  such  decay  is  a  normal  accompaniment  of 
senility.  No  one  nowadays  would  question  the  accu- 
racy of  this  observation,  but  the  scientific  world  was 

400 


PROGRESS   IN   EXPERIMENTAL   PSYCHOLOGY 

not  quite  ready  for  it  in  1825  ;  for  when  Desmoulins  an- 
nounced his  discovery  to  the  French  Academy,  that 
august  and  somewhat  patriarchal  body  was  moved  to 
quite  unscientific  wrath,  and  forbade  the  young  icono- 
clast the  privilege  of  further  hearings.  From  which  it 
is  evident  that  the  partially  liberated  spirit  of  the  new 
psychology  had  by  no  means  freed  itself  altogether,  at 
the  close  of  the  first  quarter  of  our  century,  from  the 
metaphysical  cobwebs  of  its  long  incarceration. 


ii 

While  studies  of  the  brain  were  thus  being  inaugu- 
rated, the  nervous  system,  which  is  the  channel  of  com- 
munication between  the  brain  and  the  outside  world, 
was  being  interrogated  with  even  more  tangible  results. 
The  inaugural  discovery  was  made  in  1811  by  Dr. 
(afterwards  Sir  Charles)  Bell,  the  famous  English  sur- 
geon and  experimental  physiologist.  It  consisted  of 
the  observation  that  the  anterior  roots  of  the  spinal 
nerves  are  given  over  to  the  function  of  conveying 
motor  impulses  from  the  brain  outward,  whereas  the 
posterior  roots  convey  solely  sensory  impulses  to  the 
brain  from  without.  Hitherto  it  had  been  supposed 
that  all  nerves  have  a  similar  function,  and  the  peculiar 
distribution  of  the  spinal  nerves  had  been  an  unsolved 
puzzle. 

Bell's  discovery  was  epochal;  but  its  full  significance 
was  not  appreciated  for  a  decade,  nor,  indeed,  was  its 
validity  at  first  admitted.  In  Paris,  in  particular,  then 
the  court  of  final  appeal  in  all  matters  scientific,  the  al- 
leged discovery  was  looked  at  askance,  or  quite  ignored. 
But  in  1823  the  subject  was  taken  up  by  the  recognized 
2c  401,- 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 


leader  of  French  physiology — Francois  Magendie — in 
the  course  of  his  comprehensive  experimental  studies  of 
the  nervous  system,  and  Bell's  conclusions  were  subject- 
ed to  the  most  rigid  experimental  tests,  and  found  alto- 
gether valid.  Bell  himself, 
meanwhile,  had  turned  his 
attention  to  the  cranial 
nerves,  and  had  proved 
that  these  also  are  divisible 
into  two  sets — sensory  and 
motor.  Sometimes,  indeed, 
the  two  sets  of  filaments 
are  combined  into  one  nerve 
cord,  but,  if  traced  to  their 
origin,  these  are  found  to 
arise  from  different  brain 
centres.  Thus  it  was  clear 
that  a  hitherto  unrecog- 
nized duality  of  function 
pertains  to  the  entire  extra- 
cranial  nervous  system. 

Any  impulse  sent  from  the  periphery  to  the  brain  must 
be  convej^ed  along  a  perfectly  definite  channel ;  the 
response  from  the  brain,  sent  out  to  the  peripheral 
muscles,  must  traverse  an  equally  definite  and  altogether 
different  course.  If  either  channel  is  interrupted — as  by 
the  section  of  its  particular  nerve  tract — the  correspond- 
ing message  is  denied  transmission  as  effectually  as  an 
electric  current  is  stopped  by  the  section  of  the  trans- 
mitting wire. 

Experimenters  everywhere  soon  confirmed  the  obser- 
vations of  Bell  and  Magendie ;  and,  as  always  happens 
after  a  great  discovery,  a  fresh  impulse  was  given  to  in- 

402 


SIR  CHARLES  BELL 
By  permission  of  G.  Bell  and  Sons,  London 


PROGRESS   IN   EXPERIMENTAL   PSYCHOLOGY 

vestigations  in  allied  fields.  Nevertheless,  a  full  decade 
elapsed  before  another  discovery  of  comparable  impor- 
tance was  made.  Then  Marshall  Hall,  the  most  famous 
of  English  physicians  of  his  day,  made  his  classical  ob- 
servations on  the  phenomena  that  henceforth  were  to  be 
known  as  reflex  action.  In  1832,  while  experimenting 


nil 


FRANQOIS   MAGENDTE 

one  day  with  a  decapitated  newt,  he  observed  that  the 
headless  creature's  limbs  would  contract  in  direct  re- 
sponse to  certain  stimuli.  Such  a  response  could  no 
longer  be  secured  if  the  spinal  nerves  supplying  a  part 
were  severed.  Hence  it  was  clear  that  responsive  cen- 
tres exist  in  the  spinal  cord  capable  of  receiving  a  sen- 
sory message,  and  of  transmitting  a  motor  impulse  in 
reply — a  function  hitherto  supposed  to  be  reserved  for 

403 


THE  STORY   OF  NINETEENTH-CENTURY   SCIENCE 

the  brain.  Further  studies  went  to  show  that  such  phe- 
nomena of  reflex  action  on  the  part  of  centres  lying  out- 
side the  range  of  consciousness,  both  in  the  spinal  cord 
and  in  the  brain  itself,  are  extremely  common  ;  that,  in 
short,  they  enter  constantly  into  the  activities  of  every 
living  organism,  and  have  a  most  important  share  in  the 
sum  total  of  vital  movements.  Hence,  Hall's  discovery 
must  always  stand  as  one  of  the  great  mile-stones  of  the 
advance  of  neurological  science. 

All  these  considerations  as  to  nerve  currents  and 
nerve  tracts  becoming  stock  knowledge  of  science,  it 
was  natural  that  interest  should  become  stimulated  as 
to  the  exact  character  of  these  nerve  tracts  in  them- 
selves ;  and  all  the  more  natural  in  that  the  perfected 
microscope  was  just  now  claiming  all  fields  for  its  own. 
A  troop  of  observers  soon  entered  upon  the  study  of  the 
nerves ;  and  the  leader  here,  as  in  so  many  other  lines 
of  microscopical  research,  was  no  other  than  Theodor 
Schwann.  Through  his  efforts,  and  with  the  invaluable 
aid  of  such  other  workers  as  Remak,  Purkinje,  Henle, 
Miiller,  and  the  rest,  all  the  mystery  as  to  the  general 
characteristics  of  nerve  tracts  was  cleared  away.  It 
came  to  be  known  that  in  its  essentials  a  nerve  tract  is 
a  tenuous  fibre  or  thread  of  protoplasm,  stretching  be- 
tween two  terminal  points  in  the  organism — one  of  such 
termini  being  usually  a  cell  of  the  brain  or  spinal  cord  ; 
the  other,  a  distribution  point  at  or  near  the  periphery — 
for  example,  in  a  muscle  or  in  the  skin.  Such  a  fibril  may 
have  about  it  a  protective  covering,  which  is  known  as  the 
sheath  of  Schwann ;  but  the  fibril  itself  is  the  essential 
nerve  tract ;  and  in  many  cases,  as  Remak  presently  dis- 
covered, the  sheath  is  dispensed  with,  particularly  in 
case  of  the  nerves  of  the  so-called  sympathetic  system. 

-    404 


PROGRESS    IN   EXPERIMENTAL  PSYCHOLOGY 

This  sympathetic  system  of  ganglia  and  nerves,  by- 
the-bye,  had  long  been  a  puzzle  to  the  physiologists.  Its 
ganglia,  the  seeming  centres  of  the  system,  usually  mi- 
nute in  size,  and  never  very  large,  are  found  everywhere 
through  the  organism,  but  in  particular  are  gathered 
into  a  long  double  chain  which  lies  within  the  body  cav- 
ity, outside  the  spinal  column,  and  represents  the  sole 
nervous  system  of  the  non-vertebrated  organisms.  Fi- 
brils from  these  ganglia  were  seen  to  join  the  cranial 
and  spinal  nerve  fibrils,  and  to  accompany  them  every- 
where, but  what  special  function  they  subserved  was 
long  a  mere  matter  of  conjecture,  and  led  to  many  ab- 
surd speculations.  Fact  was  not  substituted  for  conject- 
ure until  about  the  year  1851,  when  the  great  French- 
man Claude  Bernard  conclusively  proved  that  at  least 
one  chief  function  of  the  sympathetic  fibrils  is  to  cause 
contraction  of  the  walls  of  the  arterioles  of  the  system, 
thus  regulating  the  blood-supply  of  any  given  part.  Ten 
years  earlier  Henle  had  demonstrated  the  existence  of 
annular  bands  of  muscle  fibres  in  the  arterioles,  hitherto 
a  much  mooted  question,  and  several  tentative  explana- 
tions of  the  action  of  these  fibres  had  been  made,  par- 
ticularly by  the  brothers  Weber,  by  Stilling,  who,  as 
early  as  1840,  had  ventured  to  speak  of  "vaso-motor" 
nerves,  and  by  Schiff,  who  was  hard  upon  the  same 
track  at  the  time  of  Bernard's  discovery.  But  a  clear 
light  was  not  thrown  on  the  subject  until  Bernard's  ex- 
periments were  made  in  1851.  The  experiments  were 
soon  after  confirmed  and  extended  by  Brown-Sequard, 
Waller,  Budge,  and  numerous  others,  and  henceforth 
physiologists  felt  that  they  understood  how  the  blood- 
supply  of  any  given  part  is  regulated  by  the  nervous 
system. 

405 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

In  reality,  however,  they  had  learned  only  half  the 
story,  as  Bernard  himself  proved  only  a  few  years  later 
by  opening  up  a  new  and  quite  unsuspected  chapter. 
While  experimenting  in  1858  he  discovered  that  there 
are  certain  nerves  supplying  the  heart  which,  if  stimu- 
lated, cause  that  organ  to  relax  and  cease  beating.  As 
the  heart  is  essentially  nothing  more  than  an  aggrega- 
tion of  muscles,  this  phenomenon  was  utterly  puzzling 
and  without  precedent  in  the  experience  of  physi- 
ologists. An  impulse  travelling  along  a  motor  nerve 
had  been  supposed  to  be  able  to  cause  a  muscular  con- 
traction and  to  do  nothing  else ;  yet  here  such  an  im- 
pulse had  exactly  the  opposite  effect.  The  only  tenable 
explanation  seemed  to  be  that  this  particular  impulse 
must  arrest  or  inhibit  the  action  of  the  impulses  that 
ordinarily  cause  the  heart  muscles  to  contract.  But  the 
idea  of  such  inhibition  of  one  impulse  by  another  was 
utterly  novel,  and  at  first  difficult  to  comprehend. 
Gradually,  however,  the  idea  took  its  place  in  the  cur- 
rent knowledge  of  nerve  physiology,  and  in  time  it  came 
to  be  understood  that  what  happens  in  the  case  of  the 
heart  nerve-supply  is  only  a  particular  case  under  a  very 
general,  indeed  universal,  form  of  nervous  action.  Grow- 
ing out  of  Bernard's  initial  discovery  came  the  final  un- 
derstanding that  the  entire  nervous  system  is  a  mechan- 
ism of  centres  subordinate  and  centres  superior,  the 
action  of  the  one  of  which  may  be  counteracted  and 
annulled  in  effect  by  the  action  of  the  other.  This  ap- 
plies not  merely  to  such  physical  processes  as  heart- 
beats and  arterial  contraction  and  relaxing,  but  to  the 
most  intricate  functionings  which  have  their  counterpart 
in  psychical  processes  as  well.  Thus  the  observation  of 
the  inhibition  of  the  heart's  action  by  a  nervous  impulse 

406 


PROGRESS    IN   EXPERIMENTAL   PSYCHOLOGY 

furnished  the  point  of  departure  for  studies  that  led  to 
a  better  understanding  of  the  modus  operand!  of  the 
mind's  activities  than  had  ever  previously  been  attained 
by  the  most  subtle  of  psychologists. 


in 

The  work  of  the  nerve  physiologists  had  thus  an  im- 
portant bearing  on  questions  of  the  mind.  But  there 
was  another  company  of  workers  of  this  period  who 
made  an  even  more  direct  assault  upon  the  "  citadel  of 
thought."  A  remarkable  school  of  workers  had  devel- 
oped in  Germany,  the  leaders  being  men  who,  having 
more  or  less  of  innate  metaphysical  bias  as  a  national 
birthright,  had  also  the  instincts  of  the  empirical  scien- 
tist, and  whose  educational  equipment  included  a  pro- 
found knowledge  not  alone  of  physiology  and  psycholo- 
gy, but  of  physics  and  mathematics  as  well.  These  men 
undertook  the  novel  task  of  interrogating  the  relations 
of  body  and  mind  from  the  stand-point  of  physics. 
They  sought  to  apply  the  vernier  and  the  balance,  as  far 
as  might  be,  to  the  intangible  processes  of  mind. 

The  movement  had  its  precursory  stages  in  the  early 
part  of  the  century,  notably  in  the  mathematical  psy- 
chology of  Herbart,but  its  first  definitive  output  to  attract 
general  attention  came  from  the  master-hand  of  Hermann 
Helmholtz  in  1851.  It  consisted  of  the  accurate  measure- 
ment of  the  speed  of  transit  of  a  nervous  impulse  along 
a  nerve  tract.  To  make  such  measurement  had  been  re- 
garded as  impossible,  it  being  supposed  that  the  flight  of 
the  nervous  impulse  was  practically  instantaneous.  But 
Helmholtz  readily  demonstrated  the  contrary,  showing 
that  the  nerve  cord  is  a  relatively  sluggish  message- 

407 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

bearer.  According  to  his  experiments,  first  performed 
upon  the  frog,  the  nervous  "current"  travels  less  than 
one  hundred  feet  per  second.  Other  experiments  per- 
formed soon  afterward  by  Helmholtz  himself,  and  by 


EMIL   DU    BOIS   RAYMOND 

various  followers,  chief  among  whom  was  Du  Bois-Re\T- 
mond,  modified  somewhat  the  exact  figures  at  first  ob- 
tained, but  did  not  change  the  general  bearings  of  the 
early  results.  Thus  the  nervous  impulse  was  shown  to 
be  something  far  different,  as  regards  speed  of  transit, 
at  any  rate,  from  the  electric  current  to  which  it  had 

408 


PROGRESS   IN   EXPERIMENTAL  PSYCHOLOGY 

been  so  often  likened.  An  electric  current  would  flash 
half-way  round  the  globe  while  a  nervous  impulse  could 
travel  the  length  of  the  human  body — from  a  man's  foot 
to  his  brain. 

The  tendency  to  bridge  the  gulf  that  hitherto  had 
separated  the  physical  from  the  psychical  world  was 
further  evidenced  in  the  following  decade  by  Helmholtz's 
remarkable  but  highly  technical  study  of  the  sensations 
of  sound  and  of  color  in  connection  with  their  physical 
causes,  in  the  course  of  which  he  revived  the  doctrine 
of  color  vision  which  that  other  great  physiologist  and 
physicist,  Thomas  Young,  had  advanced  half  a  century 
before.  The  same  tendency  was  further  evidenced  by 
the  appearance,  in  1852,  of  Dr.  Hermann  Lotze's  famous 
Medizinische  Psychologic,  oder  Physiologie  der  Seele, 
with  its  challenge  of  the  old  myth  of  a  "  vital  force." 
But  the  most  definitive  expression  of  the  new  movement 
was  signalized  in  1860,  when  Gustav  Fechner  published 
his  classical  work  called  Psychophysik.  That  title  in- 
troduced a  new  word  into  the  vocabulary  of  science. 
Fechner  explained  it  by  saying,  "I  mean  by  psycho- 
physics  an  exact  theory  of  the  relation  between  spirit 
and  body,  and,  in  a  general  way,  between  the  physical 
and  the  psychic  worlds."  The  title  became  famous,  and 
the  brunt  of  many  a  controversy.  So  also  did  another 
phrase  which  Fechner  introduced  in  the  course  of  his 
book— the  phrase  "  physiological  psychology."  In  mak- 
ing that  happy  collocation  of  words  Fechner  virtually 
christened  a  new  science. 

The  chief  purport  of  this  classical  book  of  the  German 
psycho-physiologist  was  the  elaboration  and  explication 
of  experiments  based  on  a  method  introduced  more  than 
twenty  years  earlier  by  his  countryman  E.  H.  "Weber,  but 

409 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

which  hitherto  had  failed  to  attract  the  attention  it  de- 
served. The  method  consisted  of  the  measurement  and 
analysis  of  the  definite  relation  existing  between  exter- 
nal stimuli  of  varying  degrees  of  intensity  (various  sounds, 
for  example)  and  the  mental  states  they  induce.  Weber's 
experiments  grew  out  of  the  familiar  observation  that  the 
nicety  of  our  discriminations  of  various  sounds,  weights, 
or  visual  images  depends  upon  the  magnitude  of  each 
particular  cause  of  a  sensation  in  its  relation  with  other 
similar  causes.  Thus,  for  example,  we  cannot  see  the 
stars  in  the  daytime,  though  they  shine  as  brightly  then 
as  at  night.  Again,  we  seldom  notice  the  ticking  of  a 
clock  in  the  daytime,  though  it  may  become  almost  pain- 
fully audible  in  the  silence  of  the  night.  Yet  again,  the 
difference  between  an  ounce  weight  and  a  two- ounce 
weight  is  clearly  enough  appreciable  when  we  lift  the 
two,  but  one  cannot  discriminate  in  the  same  way  be- 
tween a  five -pound  weight  and  a  w eight  of  one  ounce 
over  five  pounds. 

This  last  example,  and  similar  ones  for  the  other  senses, 
gave  Weber  the  clew  to  his  novel  experiments.  Reflec- 
tion upon  every- day  experiences  made  it  clear  to  him 
that  whenever  we  consider  two  visual  sensations,  or  two 
auditory  sensations,  or  two  sensations  of  weight,  in  com- 
parison one  with  another,  there  is  always  a  limit  to  the 
keenness  of  our  discrimination,  and  that  this  degree  of 
keenness  varies,  as  in  the  case  of  the  weights  just  cited, 
with  the  magnitude  of  the  exciting  cause. 

Weber  determined  to  see  whether  these  common  ex- 
periences could  be  brought  within  the  pale  of  a  general 
law.  His  method  consisted  of  making  long  series  of  ex- 
periments aimed  at  the  determination,  in  each  case,  of 
what  came  to  be  spoken  of  as  the  least  observable  dif- 

410 


PROGRESS   IN   EXPERIMENTAL   PSYCHOLOGY 

ference  between  the  stimuli.  Thus  if  one  holds  an  ounce 
weight  in  each  hand,  and  has  tiny  weights  added  to  one 
of  them,  grain  by  grain,  one  does  not  at  first  perceive  a 
difference ;  but  presently,  on  the  addition  of  a  certain 
grain,  he  does  become  aware  of  the  difference.  Noting 
now  how  many  grains  have  been  added  to  produce 
this  effect,  we  have  the  weight  which  represents  the 
least  appreciable  difference  when  the  standard  is  one 
ounce. 

Now  repeat  the  experiment,  but  let  the  weights  be 
each  of  five  pounds.  Clearly  in  this  case  we  shall  be 
obliged  to  add  not  grains,  but  drachms,  before  a  differ- 
ence between  the  two  heavy  weights  is  perceived.  But 
whatever  the  exact  amount  added,  that  amount  repre- 
sents the  stimulus  producing  a  just  perceivable  sensation 
of  difference  when  the  standard  is  five  pounds.  And  so 
on  for  indefinite  series  of  weights  of  varying  magnitudes. 
Now  came  Weber's  curious  discovery.  Not  only  did  he 
find  that  in  repeated  experiments  with  the  same  pair  of 
weights  the  measure  of  "just  perceivable  difference"  re- 
mained approximately  fixed,  but  he  found,  further,  that 
a  remarkable  fixed  relation  exists  between  the  stimuli  of 
different  magnitude.  If,  for  example,  he  had  found  it 
necessary,  in  the  case  of  the  ounce  weights,  to  add  one- 
fiftieth  of  an  ounce  to  the  one  before  a  difference  was 
detected,  he  found  also,  in  the  case  of  the  five-pound 
weights,  that  one-fiftieth  of  five  pounds  must  be  added 
before  producing  the  same  result.  And  so  of  all  other 
weights ;  the  amount  added  to  produce  the  stimulus  of 
"least  appreciable  difference"  always  bore  the  same 
mathematical  relation  to  the  magnitude  of  the  weight 
used,  be  that  magnitude  great  or  small. 

Weber  found  that  the  same  thing  holds  good  for  the 

411 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

stimuli  of  the  sensations  of  sight  and  of  hearing,  the  dif- 
ferential stimulus  bearing  always  a  fixed  ratio  to  the 
total  magnitude  of  the  stimuli.  Here,  then,  was  the  law 
he  had  sought. 

Weber's  results  were  definite  enough,  and  striking 
enough,  yet  they  failed  to  attract  any  considerable  meas- 
ure of  attention  until  they  were  revived  and  extended 
by  Fechner,  and  brought  before  the  world  in  the  famous 
work  on  psycho-physics.  Then  they  precipitated  a  veri- 
table melee.  Fechner  had  not  alone  verified  the  earlier 
results  (with  certain  limitations  not  essential  to  the  pres- 
ent consideration),  but  had  invented  new  methods  of 
making  similar  tests,  and  had  reduced  the  whole  ques- 
tion to  mathematical  treatment.  He  pronounced  Weber's 
discovery  the  fundamental  law  of  psycho -physics.  In 
honor  of  the  discoverer,  he  christened  it  Weber's  Law. 
He  clothed  the  law  in  words  and  in  mathematical  for- 
mulae, and,  so  to  say,  launched  it  full  tilt  at  the  heads 
of  the  psychological  world.  It  made  a  fine  commotion, 
be  assured,  for  it  was  the  first  widely  heralded  bulletin 
of  the  new  psychology  in  its  march  upon  the  strongholds 
of  the  time-honored  metaphysics.  The  accomplishments 
of  the  microscopists  and  the  nerve  physiologists  had  been 
but  preliminary — mere  border  skirmishes  of  uncertain 
import.  But  here  was  proof  that  the  iconoclastic  move- 
ment meant  to  invade  the  very  heart  of  the  sacred  ter- 
ritory of  mind— a  territory  from  which  tangible  objec- 
tive fact  had  been  supposed  to  be  forever  barred. 

Hardly  had  the  alarm  been  sounded,  however,  before 
a  new  movement  was  made.  While  Fechner's  book  was 
fresh  from  the  press,  steps  were  being  taken  to  extend 
the  methods  of  the  physicist  in  yet  another  way  to  the 
intimate  processes  of  the  mintl.  As  Helmholtz  had  shown 

412 


PROGRESS   IN  EXPERIMENTAL   PSYCHOLOGY 

the  rate  of  nervous  impulsion  along  the  nerve  tract  to 
be  measurable,  it  was  no\v  sought  to  measure  also  the 
time  required  for  the  central  nervous  mechanism  to  per- 
form its  work  of  receiving  a  message  and  sending  out  a 


GUSTAV  THEODOR  FECHNER 

response.  This  was  coming  down  to  the  very  threshold 
of  mind.  The  attempt  was  first  made  by  Professor 
Bonders,  in  1861,  but  definitive  results  were  only  ob- 
tained after  many  years  of  experiment  on  the  part  of  a 
host  of  observers.  The  chief  of  these,  and  the  man  who 
has  stood  in  the  forefront  of  the  new  movement,  and 

413 


-     THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

has  been  its  recognized  leader  throughout  the  remainder 
of  the  century,  is  Dr.  Wilhelm  Wundt,  of  Leipzig. 

The  task  was  not  easy,  but,  in  the  long  run,  it  was 
accomplished.  Not  alone  was  it  shown  that  the  nerve 
centre  requires  a  measurable  time  for  its  operations,  but 
much  was  learned  as  to  conditions  that  modify  this 
time.  Thus  it  was  found  that  different  persons  vary  in 
the  rate  of  their  central  nervous  activity  —  which  ex- 
plained the  "  personal  equation "  that  the  astronomer 
Bessel  had  noted  a  half-century  before.  It  was  found, 
too,  that  the  rate  of  activity  varies  also  for  the  same 
person  under  different  conditions,  becoming  retarded, 
for  example,  under  influence  of  fatigue,  or  in  case  of 
certain  diseases  of  the  brain.  All  details  aside,  the  es- 
sential fact  emerges,  as  an  experimental  demonstration, 
that  the  intellectual  processes — sensation,  apperception, 
volition — are  linked  irrevocably  with  the  activities  of 
the  central  nervous  tissues,  and  that  these  activities,  like 
all  other  physical  processes,  have  a  time  element.  To 
that  old  school  of  psychologists,  who  scarcely  cared 
more  for  the  human  head  than  for  the  heels — being  in- 
terested only  in  the  mind— such  a  linking  of  mind  and 
body  as  was  thus  demonstrated  was  naturally  disquiet- 
ing. But  whatever  the  inferences,  there  was  no  escap- 
ing the  facts. 

Of  course  this  new  movement  has  not  been  confined 
to  Germany.  Indeed,  it  had  long  had  exponents  else- 
where. Thus  in  England,  a  full  century  earlier,  Dr. 
Hartley  had  championed  the  theory  of  the  close  and  in- 
dissoluble dependence  of  mind  upon  the  brain,  and 
formulated  a  famous  vibration  theory  of  association  that 
still  merits  careful  consideration.  Then,  too,  in  France, 
at  the  beginning  of  the  century,  there  was  Dr.  Cabanis 

414 


PROGRESS   IN   EXPERIMENTAL  PSYCHOLOGY 

with  his  tangible,  if  crudely  phrased,  doctrine  that  the 
brain  digests  impressions  and  secretes  thought  as  the 
stomach  digests  food  and  the  liver  secretes  bile.  More- 
over, Herbert  Spencer's  Principles  of  Psychology,  with- 
its  avowed  co-ordination  of  mind  and  body  and  its  vital- 
izing theory  of  evolution,  appeared  in  1855,  half  a  decade 
before  the  work  of  Fechner.  But  these  influences, 
though  of  vast  educational  value,  were  theoretical  rather 
than  demonstrative,  and  the  fact  remains  that  the  experi- 
mental work  which  first  attempted  to  gauge  mental  opera- 
tions by  physical  principles  was  mainly  done  in  Germany. 
Wundt's  Physiological  Psychology,  with  its  full  pre-\ 
liminary  descriptions  of  the  anatomy  of  the  nervous  sys- 
tem, gave  tangible  expression  to  the  growth  of  the  new 
movement  in  18Y4 ;  and  four  years  later,  with  the  open- 
ing of  his  laboratory  of  Physiological  Psychology  at  the 
University  of  Leipzig,  the  new  psychology  may  be  said 
to  have  gained  a  permanent  foothold,  and  to  have  forced 
itself  into  official  recognition.  From  then  on  its  con- 
quest of  the  world  was  but  a  matter  of  time. 

It  should  be  noted,  however,  that  there  is  one  other 
method  of  strictly  experimental  examination  of  the  men- 
tal field,  latterly  much  in  vogue,  which  had  a  different 
origin.  This  is  the  scientific  investigation  of  the  phe- 
nomena of  hypnotism.  This  subject  was  rescued  from 
the  hands  of  charlatans,  rechristened,  and  subjected  to 
accurate  investigation  by  Dr.  James  Braid,  of  Manches- 
ter, as  early  as  1841.  But  his  results,  after  attracting 
momentary  attention,  fell  from  view,  and,  despite  desul- 
tory efforts,  the  subject  was  not  again  accorded  a  gen- 
eral hearing  from  the  scientific  world  until  1878,  when 
Dr.  Charcot  took  it  up  at  the  Salpetriere  in  Paris,  fol- 
lowed soon  afterwards  by  Dr.  Rudolf  Heidenhain,  of 

415 


THE  STORY   OF  NINETEENTH-CENTURY   SCIENCE 

Breslau,  and  a  host  of  other  experimenters.  The  value 
of  the  method  in  the  study  of  mental  states  was  soon 
apparent.  Most  of  Braid's  experiments  were  repeated, 
and  in  the  main  his  results  were  confirmed.  His  expla- 
nation of  hypnotism,  or  artificial  somnambulism,  as  a 


JEAN   MARTIN    CIIAKCOT 

self-induced  state,  independent  of  any  occult  or  super- 
sensible influence,  soon  gained  general  credence.  His 
belief  that  the  initial  stages  are  due  to  fatigue  of  ner- 
vous centres,  usually  from  excessive  stimulation,  has  not 
been  supplanted,  though  supplemented  by  notions  grow- 

416   . 


PltOGKESS   IN   EXPERIMENTAL   PSYCHOLOGY 

ing  out  of  the  new  knowledge  as  to  subconscious  men- 
tality in  general,  and  the  inhibitory  influence  of  one 
centre  over  another  in  the  central  nervous  mechanism. 


IV 

These  studies  of  the  psychologists  and  pathologists 
bring  the  relations  of  mind  and  body  into  sharp  relief. 
But  even  more  definite  in  this  regard  was  the  work  of 
the  brain  physiologists.  Chief  of  these,  during  the  mid- 
dle period  of  the  century,  was  the  man  who  is  some- 
times spoken  of  as  the  "  father  of  brain  physiology," 
Marie  Jean  Pierre  Flourens,  of  the  Jardin  des  Plantes 
of  Paris,  the  pupil  and  worthy  successor  of  Magendie. 
His  experiments  in  nerve  physiology  were  begun  in  the 
first  quarter  of  the  century,  but  his  local  experiments 
upon  the  brain  itself  were  not  culminated  until  about 
1842.  At  this  time  the  old  dispute  over  phrenology  had 
broken  out  afresh,  and  the  studies  of  Flourens  were 
aimed,  in  part  at  least,  at  the  strictly  scientific  investi- 
gation of  this  troublesome  topic. 

In  the  course  of  these  studies  Flourens  discovered  that 
in  the  medulla  otlongata,  the  part  of  the  brain  which 
connects  that  organ  with  tne  spinal  cord,  there  is  a  cen- 
tre of  minute  size  which  cannot  be  injured  in  the  least 
without  causing  the  instant  death  of  the  animal  oper- 
ated upon.  It  may  be  added  that  it  is  this  spot  which 
is  reached  by  the  needle  of  the  garroter  in  Spanish  exe- 
cutions, and  that  the  same  centre  also  is  destroyed  when 
a  criminal  is  "successfully"  hanged,  this  time  by  the 
forced  intrusion  of  a  process  of  the  second  cervical  ver- 
tebra. Flourens  named  this  spot  the  "  vital  knot."  Its 
extreme  importance,  as  is  now  understood,  is  due  to  the 
So  417 


THE   STOttY   OF  NINETEENTH-CENTURY  SCIENCE 

fact  'that  it  is  the  centre  of  nerves  that  supply  the 
heart;  but  this  simple  explanation,  annulling  the  con- 
ception of  a  specific  "  life  centre,"  was  not  at  once  ap- 
parent. 

Other  experiments  of  Flourens  seemed  to  show  that 
the  cerebellum  is  the  seat  of  the  centres  that  co-ordinate 
muscular  activities,  and  that  the  higher  intellectual  fac- 
ulties are  relegated  to  the  cerebrum.  But  beyond  this, 
as  regards  localization,  experiment  faltered.  Negative 
results,  as  regards  specific  faculties,  were  obtained  from 
all  localized  irritations  of  the  cerebrum,  and  Flourens 
was  forced  to  conclude  that  the  cerebral  lobe,  while 
being  undoubtedly  the  seat  of  higher  intellection,  per- 
forms its  functions  with  its  entire  structure.  This  con- 
clusion, which  incidentally  gave  a  quietus  to  phrenology, 
was  accepted  generally,  and  became  the  stock  doctrine 
of  cerebral  physiology  for  a  generation. 

It  will  be  seen,  however,  that  these  studies  of  Flourens 
had  a  double  bearing.  They  denied  localization  of 
cerebral  functions,  but  they  demonstrated  the  localiza- 
tion of  certain  nervous  processes  in  other  portions  of  the 
brain.  On  the  whole,  then,  they  spoke  positively  for 
the  principle  of  localization  of  function  in  the  brain,  for 
which  a  certain  number  of  students  contended ;  while 
their  evidence  against  cerebral  localization  was  only 
negative.  There  was  here  and  there  an  observer  who 
felt  that  this  negative  testimony  was  not  conclusive.  In 
particular,  the  German  anatomist  Meynert,  who  had 
studied  the  disposition  of  nerve  tracts  in  the  cerebrum, 
was  led  to  believe  that  the  anterior  portions  of  the  cere- 
brum must  have  motor  functions  in  preponderance ;  the 
posterior  portions,  sensory  functions.  Somewhat  simi- 
lar conclusions  were  reached  also  by  Dr.  Hughlings- 

418. 


PROGRESS   IN  EXPERIMENTAL  PSYCHOLOGY 

Jackson,  in  England,  from  his  studies  of  epilepsy.  But 
no  positive  evidence  was  forth-coming  until  1861,  when 
Dr.  Paul  Broca  brought  before  the  Academy  of  Medi- 
cine in  Paris  a  case  of  brain  lesion  which  he  regarded  as 
having  most  important  bearings  on  the  question  of  cere- 
bral localization. 

The  case  was  that  of  a  patient  at  the  Bicetre,  who  for 
twenty  years  had  been  deprived  of  the  power  of  speech, 
seemingly  through  loss  of  memory  of  words.  In  1861 
this  patient  died,  and  an  autopsy  revealed  that  a  certain 
convolution  of  the  left  frontal  lobe  of  his  cerebrum  had 
been  totally  destroyed  by  disease,  the  remainder  of  his 
brain  being  intact.  Broca  felt  that  this  observation 
pointed  strongly  to  a  localization  of  the  memory  of 
words  in  a  definite  area  of  the  brain.  Moreover,  it 
transpired  that  the  case  was  not  without  precedent.  As 
long  ago  as  1825  Dr.  Boillard  had  been  led,  through 
pathological  studies,  to  locate  definitely  a  centre  for  the 
articulation  of  words  in  the  frontal  lobe,  and  here  and 
there  other  observers  had  made  tentatives  in  the  same 
direction.  Boillard  had  even  followed  the  matter  up 
with  pertinacity,  but  the  world  was  not  ready  to  listen 
to  him.  Now,  however,  in  the  half -decade  that  fol- 
lowed Broca's  announcements,  interest  rose  to  fever- 
heat,  and  through  the  efforts  of  Broca,  Boillard,  and 
numerous  others  it  was  proved  that  a  veritable  centre 
having  a  strange  domination  over  the  memory  of  articu- 
late words  has  its  seat  in  the  third  convolution  of  the 
frontal  lobe  of  the  cerebrum,  usually  in  the  left  hemi- 
sphere. That  part  of  the  brain  has  since  been  known  to 
the  English-speaking  world  as  the  convolution  of  Broca, 
a  name  which,  strangely  enough,  the  discoverer's  com- 
patriots have  been  slow  to  accept. 

419  ,f 


THE   STORY   OF  NINETEENTll-CENTUltY   SCIENCE 

This  discovery  very  naturally  reopened  the  entire 
subject  of  brain  localization.  It  was  but  a  short  step  to 
the  inference  that  there  must  be  other  definite  centres 
worth  the  seeking,  and  various  observers  set  about 
searching  for  them.  In  1867  a  clew  was  gained  by  Eck- 
hard,  who,  repeating  a  forgotten  experiment  of  Haller 
and  Zinn  of  the  previous  century,  removed  portions  of 
the  brain  cortex  of  animals,  with  the  result  of  producing 
convulsions.  But  the  really  vital  departure  was  made 
in  1870  by  the  German  investigators  Fritsch  and  Hitzig, 
who,  by  stimulating  definite  areas  of  the  cortex  of  ani- 
mals with  a  galvanic  current,  produced  contraction  of 
definite  sets  of  muscles  of  the  opposite  side  of  the  body. 
These  most  important  experiments,  received  at  first  with 
incredulity,  were  repeated  and  extended  in  1873  by  Dr. 
David  Ferrier,  of  London,  and  soon  afterwards  by  a 
small  army  of  independent  workers  everywhere,  prom- 
inent among  whom  were  Franck  and  Pitres  in  France, 
Munck  and  Goltz  in  Germany,  and  Horsley  and  Schafer 
in  England.  The  detailed  results,  naturally  enough, 
were  not  at  first  all  in  harmony.  Some  observers,  as 
Goltz,  even  denied  the  validity  of  the  conclusions  in  toto. 
But  a  consensus  of  opinion,  based  on  multitudes  of  ex- 
periments, soon  placed  the  broad  general  facts  for  which 
Fritsch  and  Hitzig  contended  beyond  controversy.  It 
was  found,  indeed,  that  the  cerebral  centres  of  motor 
activities  have  not  quite  the  finality  at  first  ascribed  to 
them  by  some  observers,  since  it  may  often  happen  that 
after  the  destruction  of  a  centre,  with  attending  loss  of 
function,  there  may  be  a  gradual  restoration  of  the  lost 
function,  proving  that  other  centres  have  acquired  the 
capacity  to  take  the  place  of  the  one  destroyed.  There 
are  limits  to  this  capacity  for  substitution,  however,  and 

420 


PROGRESS   IN   EXPERIMENTAL   PSYCHOLOGY 

with  this  qualification  the  definiteness  of  the  localization 
of  motor  functions  in  the  cerebral  cortex  has  become  an 
accepted  part  of  brain  physiology. 


PAUL   BROCA 


Nor  is  such  localization  confined  to  motor  centres. 
Later  experiments,  particularly  of  Ferrier  and  of  Munck, 
proved  that  the  centres  of  vision  are  equally  restricted 
in  their  location,  this  time  in  the  posterior  lobes  of  the 


THE   STORY   OF   NINETEENTH-CENTURY    SCIENCE 

brain,  and  that  hearing  has  likewise  its  local  habitation. 
Indeed,  there  is  every  reason  to  believe  that  each  form 
of  primary  sensation  is  based  on  impressions  which  main- 
ly come  to  a  definitely  localized  goal  in  the  brain.  But 
all  this,  be  it  understood,  has  no  reference  to  the  higher 
forms  of  intellection.  All  experiment  has  proved  futile 
to  localize  these  functions,  except  indeed  to  the  extent 
of  corroborating  the  familiar  fact  of  their  dependence 
upon  the  brain,  and,  somewhat  problematically,  upon 
the  anterior  lobes  of  the  cerebrum  in  particular.  But 
this  is  precisely  what  should  be  expected,  for  the  clearer 
insight  into  the  nature  of  mental  processes  makes  it  plain 
that  in  the  main  these  alleged  "  faculties "  are  not  in 
themselves  localized.  Thus,  for  example,  the  "  faculty" 
of  language  is  associated  irrevocably  with  centres  of 
vision,  of  hearing,  and  of  muscular  activity,  to  go  no 
further,  and  only  becomes  possible  through  the  associa- 
tion of  these  widely  separated  centres.  The  destruction 
of  Broca's  centre,  as  was  early  discovered,  does  not  alto- 
gether deprive  a  patient  of  his  knowledge  of  language. 
He  may  be  totally  unable  to  speak  (though  as  to  this 
there  are  all  degrees  of  variation),  and  yet  may  compre- 
hend what  is  said  to  him,  and  be  able  to  read,  think,  and 
even  write  correctly.  Thus  it  appears  that  Broca's  cen- 
tre is  peculiarly  bound  up  with  the  capacity  for  articu- 
late speech,  but  is  far  enough  from  being  the  seat  of  the 
faculty  of  language  in  its  entirety. 

In  a  similar  way,  most  of  the  supposed  isolated  "  fac- 
ulties" of  higher  intellection  appear,  upon  clearer  anal- 
ysis as  complex  aggregations  of  primary  sensations,  and 
hence  necessarily  dependent  upon  numerous  and  scattered 
centres.  Some  "  faculties,"  as  memory  and  volition,  may 
be  said  in  a  sense  to  be  primordial  endowments  of  every 

433 


PROGRESS   IN   EXPERIMENTAL   PSYCHOLOGY 

nerve  cell — even  of  every  body  cell.  Indeed,  an  ultimate 
analysis  relegates  all  intellection,  in  its  primordial  adum- 
brations, to  every  particle  of  living  matter.  But  such 
refinements  of  analysis,  after  all,  cannot  hide  the  fact 
that  certain  forms  of  higher  intellection  involve  a  pretty 
definite  collocation  and  elaboration  of  special  sensations. 
Such  specialization,  indeed,  seems  a  necessary  accompani- 
ment of  mental  evolution.  That  every  such  specialized 
function  has  its  localized  centres  of  co-ordination,  of  some 
such  significance  as  the  demonstrated  centres  of  articu- 
late speech,  can  hardly  be  in  doubt — though  this,  be  it 
understood,  is  an  induction,  not  as  yet  a  demonstration. 
In  other  words,  there  is  every  reason  to  believe  tnat  nu- 
merous "centres,"  in  this  restricted  sense,  exist  in  the 
brain  that  have  as  yet  eluded  the  investigator.  Indeed, 
the  current  conception  regards  the  entire  cerebral  cortex 
as  chiefly  composed  of  centres  of  ultimate  co-ordination 
of  impressions,  which  in  their  cruder  form  are  received 
by  more  primitive  nervous  tissues — the  basal  ganglia, 
the  cerebellum,  and  medulla,  and  the  spinal  cord.  This 
of  course  is  equivalent  to  postulating  the  cerebral  cortex 
as  the  exclusive  seat  of  higher  intellection.  This  prop- 
osition, however,  to  which  a  safe  induction  seems  to  lead, 
is  far  afield  from  the  substantiation  of  the  old  conception 
of  brain  localization,  which  was  based  on  faulty  psy- 
chology, and  equally  faulty  inductions  from  few  premises. 
The  details  of  Gall's  system,  as  propounded  by  genera- 
tions of  his  mostly  unworthy  followers,  lie  quite  beyond 
the  pale  of  scientific  discussion.  Yet,  as  I  have  said,  a  germ 
of  truth  was  there— the  idea  of  specialization  of  cerebral 
functions — and  modern  investigators  have  rescued  that 
central  conception  from  the  phrenological  rubbish  heap 
in  which  its  discoverer  unfortunately  left  it  buried. 

433 


THE  STORY   OF  NINETEENTH-CENTURY   SCIENCE 


The  common  ground  of  all  these  various  lines  of  in- 
vestigations of  pathologist,  anatomist,  physiologist,  phys- 
icist, and  psychologist  is,  clearly,  the  central  nervous 
system — the  spinal  cord  and  the  brain.  The  importance 
of  these  structures  as  the  foci  of  nervous  and  mental  ac^ 
tivities  has  been  recognized  more  and  more  with  each 
new  accretion  of  knowledge,  and  the  efforts  to  fathom 
the  secrets  of  their  intimate  structure  has  been  unceas- 
ing. For  the  earlier  students,  only  the  crude  methods 
of  gross  dissections  and  microscopical  inspection  were 
available.  These  could  reveal  something,  but  of  course 
the  inner  secrets  were  for  the  keener  insight  of  the  mi- 
croscopist  alone.  And  even  for  him  the  task  of  investi- 
gation was  far  from  facile,  for  the  central  nervous  tissues 
are  the  most  delicate  and  fragile,  and  on  many  accounts 
the  most  difficult  of  manipulation  of  any  in  the  body. 

Special  methods,  therefore,  were  needed  for  this  essay, 
and  brain  histology  has  progressed  by  fitful  impulses, 
each  forward  jet  marking  the  introduction  of  some  in- 
genious improvement  of  mechanical  technique,  which 
placed  a  new  weapon  in  the  hands  of  the  investigators. 

The  very  beginning  was  made  in  1824  by  Rolando, 
who  first  thought  of  cutting  chemically  hardened  pieces 
of  brain  tissues  into  thin  sections  for  microscopical  ex- 
amination—  the  basal  structure  upon  which  almost  all 
the  later  advances  have  been  conducted.  Miiller  pres- 
ently discovered  that  bichromate  of  potassium  in  solu- 
tion makes  the  best  of  fluids  for  the  preliminary  preser- 
vation and  hardening  of  the  tissues.  Stilling,  in  1842, 
perfected  the  method  by  introducing  the  custom  of  cut- 
ting a  series  of  consecutive  sections  of  the  same  tissue, 

424 


PROGRESS   IN   EXPERIMENTAL   PSYCHOLOGY 

in  order  to  trace  nerve  tracts  and  establish  spacial  rela- 
tions. Then  from  time  to  time  mechanical  ingenuity 
added  fresh  details  of  improvement.  It  was  found  that 
pieces  of  hardened  tissue  of  extreme  delicacy  can  be 
made  better  subject  to  manipulation  by  being  impreg- 
nated with  collodion  or  celloidine,  and  embedded  in  par- 
affine.  Latterly  it  has  become  usual  to  cut  sections  also 
from  fresh  tissues,  unchanged  by  chemicals,  by  freezing 
them  suddenly  with  vaporized  ether,  or,  better,  carbonic 
acid.  By  these  methods,  and  with  the  aid  of  perfected 
microtomes,  the  worker  of  recent  periods  avails  himself 
of  sections  of  brain  tissues  of  a  tenuousness  which  the 
early  investigators  could  not  approach. 

But  more  important  even  than  the  cutting  of  thin  sec- 
tions is  the  process  of  making  the  different  parts  of  the 
section  visible,  one  tissue  differentiated  from  another. 
The  thin  section,  as  the  early  workers  examined  it,  was 
practically  colorless,  and  even  the  crudest  details  of  its 
structure  were  made  out  with  extreme  difficulty.  Remak 
did,  indeed,  manage  to  discover  that  the  brain  tissue  is 
cellular,  as  early  as  1833,  and  Ehrenberg  in  the  same 
year  saw  that  it  is  also  fibrillar,  but  beyond  this  no  great 
advance  was  made  until  1858,  when  a  sudden  impulse 
was  received  from  a  new  process  introduced  by  Gerlach. 
The  process  itself  was  most  simple,  consisting  essentially 
of  nothing  more  than  the  treatment  of  a  microscopical 
section  with  a  solution  of  carmine.  But  the  result  was 
wonderful,  for  when  such  a  section  was  placed  under 
the  lens,  it  no  longer  appeared  homogeneous.  Sprinkled 
through  its  substance  were  seen  irregular  bodies  that  had 
taken  on  a  beautiful  color,  while  the  matrix  in  which  they 
were  embedded  remained  unstained.  In  a  word,  the  cen- 
tral nerve  cell  had  sprung  suddenly  into  clear  view. 

425 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

A  most  interesting  body  it  proved,  this. nerve  cell,  or 
ganglion  cell,  as  it  came  to  be  called.  It  was  seen  to  be 
exceedingly  minute  in  size,  requiring  high  powers  of  the 
microscope  to  make  it  visible.  It  exists  in  almost  infi- 
nite numbers,  not,  however,  scattered  at  random  through 
the  brain  and  spinal  cord.  On  the  contrary,  it  is  confined 
to  those  portions  of  the  central  nervous  masses  which  to 
the  naked  eye  appear  gray  in  color,  being  altogether 
wanting  in  the  white  substance  which  makes  up  the  chief 
mass  of  the  brain.  Even  in  the  gray  matter,  though 
sometimes  thickly  distributed,  the  ganglion  cells  are 
never  in  actual  contact  one  with  another ;  they  always 
lie  embedded  in  intercellular  tissues,  which  came  to  be 
known,  following  Virchow,  as  the  neuroglia. 

Each  ganglion  cell  was  seen  to  be  irregular  in  con- 
tour, and  to  have  jutting  out  from  it  two  sets  of  mi- 
nute fibres,  one  set  relatively  short,  indefinitely  numer- 
ous, and  branching  in  every  direction ;  the  other  set 
limited  in  number,  sometimes  even  single,  and  starting 
out  directly  from  the  cell  as  if  bent  on  a  longer  journey. 
The  numerous  filaments  came  to  be  known  as  proto- 
plasmic processes;  the  other  fibre  was  named,  after  its 
discoverer,  the  axis  cylinder  of  Deiters.  It  was  a  natural 
inference,  though  not  clearly  demonstrable  in  the  sec- 
tions, that  these  filamentous  processes  are  the  connect- 
ing links  between  the  different  nerve  cells,  and  also  the 
channels  of  communication  between  nerve  cells  and  the 
periphery  of  the  body.  The  white  substance  of  brain 
and  cord,  apparently,  is  made  up  of  such  connecting 
fibres,  thus  bringing  the  different  ganglion  cells  every- 
where into  communication  one  with  another. 

In  the  attempt  to  trace  the  connecting  nerve  tracts 
through  this  white  substance  by  either  macroscopical  or 

426 


PROGRESS   IN   EXPERIMENTAL   PSYCHOLOGY 

microscopical  methods,  most  important  aid  is  given  by 
a  method  originated  by  Waller  in  1852.  Earlier  than 
that,  in  1839,  Nasse  had  discovered  that  a  severed  nerve 
cord  degenerates  in  its  peripheral  portions.  Waller  dis- 
covered that  every  nerve  fibre,  sensory  or  motor,  has  a 
nerve  cell  to  or  from  which  it  leads,  which  dominates 
its  nutrition,  so  that  it  can  only  retain  its  vitality  while 
its  connection  with  that  cell  is  intact.  Such  cells  he 
named  trophic  centres.  Certain  cells  of  the  anterior 
part  of  the  spinal  cord,  for  example,  are  the  trophic 
centres  of  the  spinal  motor  nerves.  Other  trophic  cen- 
tres, governing  nerve  tracts  in  the  spinal  cord  itself,  are 
in  the  various  regions  of  the  brain.  It  occurred  to 
Waller  that  by  destroying  such  centres,  or  by  severing 
the  connection  at  various  regions  between  a  nervous 
tract  and  its  trophic  centre,  sharply  defined  tracts  could 
be  made  to  degenerate,  and  their  location  could  subse- 
quently be  accurately  defined,  as  the  degenerated  tis- 
sues take  on  a  changed  aspect,  both  to  macroscopical 
and  microscopical  observation.  Recognition  of  this 
principle  thus  gave  the  experimenter  a  new  weapon  of 
great  efficiency  in  tracing  nervous  connections.  More- 
over, the  same  principle  has  wide  application  in  case  of 
the  human  subject  in  disease,  such  as  the  lesion  of  nerve 
tracts  or  the  destruction  of  centres  by  localized  tumors, 
by  embolisms,  or  by  traumatisms. 

All  these  various  methods  of  anatomical  examination 
combine  to  make  the  conclusion  almost  unavoidable 
that  the  central  ganglion  cells  are  the  veritable  "cen- 
tres "  of  nervous  activity  to  which  so  many  other  lines 
of  research  have  pointed.  The  conclusion  was  strength- 
ened by  experiments  of  the  students  of  motor  localiza- 
tion, which  showed  that  the  veritable  centres  of  their 

427 


THE   STORY   OF  NINETEENTH-CENTURY   SCIENCE 

discovery  lie,  demonstrably,  in  the  gray  cortex  of  the 
brain,  not  in  the  white  matter.  But  the  full  proof  came 
from  pathology.  At  the  hands  of  a  multitude  of  ob- 
servers it  was  shown  that  in  certain  well-known  diseases 
of  the  spinal  cord,  with  resulting  paralysis,  it  is  the 
ganglion  cells  themselves  that  are  found  to  be  destroyed. 
Similarly,  in  the  case  of  sufferers  from  chronic  insani- 
ties, with  marked  dementia,  the  ganglion  cells  of  the 
cortex  of  the  brain  are  found  to  have  undergone  degen- 
eration. The  brains  of  paretics  in  particular  show  such 
degeneration,  in  striking  correspondence  with  their  men- 
tal decadence.  The  position  of  the  ganglion  cell  as  the 
ultimate  centre  of  nervous  activities  was  thus  placed  be- 
yond dispute. 

Meantime,  general  acceptance  being  given  the  histo- 
logical  scheme  of  Gerlach,  according  to  which  the  mass 
of  the  white  substance  of  the  brain  is  a  mesh-work  of 
intercellular  fibrils,  a  proximal  idea  seemed  attainable  of 
the  way  in  which  the  ganglionic  activities  are  corre- 
lated, and,  through  association,  built  up,  so  to  speak, 
into  the  higher  mental  processes.  Such  a  conception  ac- 
corded beautifully  with  the  ideas  of  the  associationists, 
who  had  now  become  dominant  in  psychology.  But 
one  standing  puzzle  attended  this  otherwise  satisfactory 
correlation  of  anatomical  observations  and  psychic  anal- 
yses. It  was  this :  Since,  according  to  the  histologist, 
the  intercellular  fibres,  along  which  impulses  are  con- 
veyed, connect  each  brain  cell,  directly  or  indirectly, 
with  every  other  brain  cell  in  an  endless  mesh-work, 
how  is  it  possible  that  various  sets  of  cells  may  at  times 
be  shut  off  from  one  another?  Such  isolation  must 
take  place,  for  all  normal  ideation  depends  for  its  integ- 
rity quite  as  much  upon  the  shutting  out  of  the  great 

428 


PROGRESS   IN   EXPERIMENTAL   PSYCHOLOGY 

mass  of  associations  as  upon  the  inclusion  of  certain 
other  associations.  For  example,  a  student  in  solving  a 
mathematical  problem  must  for  the  moment  become 
quite  oblivious  to  the  special  associations  that  have  to 
do  with  geography,  natural  history,  and  the  like.  But 
does  histology  give  any  clew  to  the  way  in  which  such 
isolation  may  be  effected  ? 

Attempts  were  made  to  find  an  answer  through  con- 
sideration of  the  very  peculiar  character  of  the  blood- 
supply  in  the  brain.  Here,  as  nowhere  else,  the  ter- 
minal twigs  of  the  arteries  are  arranged  in  closed  sys- 
tems, not  anastomosing  freely  with  neighboring  systems. 
Clearly,  then,  a  restricted  area  of  the  brain  may,  through 
the  controlling  influence  of  the  vaso-motor  nerves,  be 
flushed  with  arterial  blood,  while  neighboring  parts  re- 
main relatively  anaemic.  And  since  vital  activities  un- 
questionably depend  in  part  upon  the  supply  of  arterial 
blood,  this  peculiar  arrangement  of  the  vascular  mech- 
anism may  very  properly  be  supposed  to  aid  in  the 
localized  activities  of  the  central  nervous  ganglia.  But 
this  explanation  left  much  to  be  desired— in  particular 
when  it  is  recalled  that  all  higher  intellection  must  in 
all  probability  involve  multitudes  of  widely  scattered 
centres. 

No  better  explanation  was  forth-coming,  however, 
until  the  year  1889,  when  of  a  sudden  the  mystery  was 
cleared  away  by  a  fresh  discovery.  Not  long  before 
this  the  Italian  histologist,  Dr.  Camille  Golgi,  had  dis- 
covered a  method  of  impregnating  hardened  brain  tis- 
sues with  a  solution  of  nitrate  of  silver,  with  the  result 
of  staining  the  nerve  cells  and  their  processes  almost  in- 
finitely better  than  was  possible  by  the  method  of  Ger- 
lach,  or  by  any  of  the  multiform  methods  that  other 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

workers  had  introduced.  Now  for  the  first  time  it  be- 
came possible  to  trace  the  cellular  prolongations  definite- 
ly to  their  termini,  for  the  finer  fibrils  had  not  been 
rendered  visible  by  any  previous  method  of  treatment. 
Golgi  himself  proved  that  the  set  of  fibrils  known  as 
protoplasmic  prolongations  terminate  by  free  extremi- 
ties, and  have  no  direct  connection  with  any  cell  save 
the  one  from  which  they  spring.  He  showed  also  that 
the  axis  cylinders  give  off  multitudes  of  lateral  branches 
not  hitherto  suspected.  But  here  he  paused,  missing 
the  real  import  of  the  discovery  of  which  he  was  hard 
on  the  track.  It  remained  for  the  Spanish  histologist, 
Dr.  S.  Eamon  y  Cajal,  to  follow  up  the  investigation  by 
means  of  an  improved  application  of  Golgi's  method  of 
staining,  and  to  demonstrate  that  the  axis  cylinders,  to- 
gether with  all  their  collateral  branches,  though  some- 
times extending  to  a  great  distance,  yet  finally  termi- 
nate, like  the  other  cell  prolongations,  in  arborescent 
fibrils  having  free  extremities.  In  a  word,  it  was  shown 
that  each  central  nerve  cell,  with  its  fibrillar  offshoots, 
is  an  isolated  entity.  Instead  of  being  in  physical  con- 
nection with  a  multitude  of  other  nerve  cells,  it  has  no 
direct  physical  connection  with  any  other  nerve  cell 
whatever. 

When  Dr.  Cajal  announced  his  discovery,  in  1889,  his 
revolutionary  claims  not  unnaturally  amazed  the  mass 
of  histologists.  There  were  some  few  of  them,  however, 
who  were  not  quite  unprepared  for  the  revelation ;  in 
particular  His,  who  had  half  suspected  the  independence 
of  the  cells,  because  they  seemed  to  develop  from  disso- 
ciated centres ;  and  Forel,  who  based  a  similar  suspicion 
on  the  fact  that  he  had  never  been  able  actually  to 
trace  a  fibre  from  one  cell  to  another.  These  observers 

430 


:TY 

1 

PROGRESS   IN   EXPERIMENTAL   PSYC 

then  came  readily  to  repeat  Cajal's  experiments.  So 
also  did  the  veteran  histologist  Kolliker,  and  soon  after- 
wards all  the  leaders  everywhere.  The  result  was  a 
practically  unanimous  confirmation  of  the  Spanish  his- 
tologist's  claims,  and  within  a  few  months  after  his  an- 
nouncements the  old  theory  of  union  of  nerve  cells  into 
an  endless  mesh-work  was  completely  discarded,  and 
the  theory  of  isolated  nerve  elements — the  theory  of 
neurons,  as  it  came  to  be  called — was  fully  established 
in  its  place. 

As  to  how  these  isolated  nerve  cells  functionate,  Dr. 
Cajal  gave  the  clew  from  the  very  first,  and  his  expla- 
nation has  met  with  universal  approval. 

In  the  modified  view,  the  nerve  cell  retains  its  old 
position  as  the  storehouse  of  nervous  energy.  Each  of 
the  filaments  jutting  out  from  the  cell  is  held,  as  before, 
to  be  indeed  a  transmitter  of  impulses,  but  a  transmit- 
ter that  operates  intermittently,  like  a  telephone  wire 
that  is  not  always  "connected,"  and,  like  that  wire,  the 
nerve  fibril  operates  by  contact  and  not  by  continuity. 
Under  proper  stimulation  the  ends  of  the  fibrils  reach 
out,  come  in  contact  with  other  end  fibrils  of  other  cells, 
and  conduct  their  destined  impulse.  Again  they  re- 
tract, and  communication  ceases  for  the  time  between 
those  particular  cells.  Meantime,  by  a  different  ar- 
rangement of  the  various  conductors,  different  sets  of 

o 

cells  are  placed  in  communication,  different  associations 
of  nervous  impulses  induced,  different  trains  of  thought 
engendered.  Each  fibril  when  retracted  becomes  a  non- 
conductor, but  when  extended  and  in  contact  with  an- 
other fibril,  or  with  the  body  of  another  cell,  it  conducts 
its  message  as  readily  as  a  continuous  filament  could  do 
—precisely  as  in  the  case  of  an  electric  wire. 

431 


THE  STORY   OF  NINETEENTH-GENT  UK  Y   SCIENCE 

This  conception,  founded  on  a  most  tangible  anatom- 
ical basis,  enables  us  to  answer  the  question  as  to  how 
ideas  are  isolated,  and  also,  as  Dr.  Cajal  points  out, 
throws  new  light  on  many  other  mental  processes.  One 
can  imagine,  for  example,  by  keeping  in  mind  the  flexi- 
ble nerve  prolongations,  how  new  trains  of  thought  may 
be  engendered  through  novel  associations  of  cells ;  how 
facility  of  thought  or  of  action  in  certain  directions  is 
acquired  through  the  habitual  making  of  certain  nerve 
cell  connections;  how  certain  bits  of  knowledge  may 
escape  our  memory,  and  refuse  to  be  found  for  a  time, 
because  of  a  temporary  incapacity  of  the  nerve  cells  to 
make  the  proper  connections ;  and  so  on  indefinitely. 
If  one  likens  each  nerve  cell  to  a  central  telephone- 
office,  each  of  its  filamentous  prolongations  to  a  tele- 
phone wire,  he  can  imagine  a  striking  analogy  between 
the  modus  operandi  of  nervous  processes  and  of  the  tel- 
ephone system.  The  utility  of  new  connections  at  the 
central  office,  the  uselessness  of  the  mechanism  when 
the  connections  cannot  be  made,  the  "  wires  in  use " 
that  retard  your  message,  perhaps  even  the  crossing  of 
wires,  bringing  you  a  jangle  of  sounds  far  different  from 
what  you  desire — all  these  and  a  multiplicity  of  other 
things  that  will  suggest  themselves  to  every  user  of  the 
telephone  may  be  imagined  as  being  almost  ludicrously 
paralleled  in  the  operations  of  the  nervous  mechanism. 
And  that  parallel,  startling  as  it  may  seem,  is  not  a  mere 
futile  imagining.  It  is  sustained  and  rendered  plausible 
by  a  sound  substratum  of  knowledge  of  the  anatomical 
conditions  under  which  the  central  nervous  mechanism 
exists,  and  in  default  of  which,  as  pathology  demonstrates 
with  no  less  certitude,  its  functionings  are  futile  to  pro- 
duce the  normal  manifestations  of  higher  intellection. 

432 


CHAPTER  XIII 
SOME  UNSOLVED  SCIENTIFIC  PROBLEMS 

IN  the  preceding  chapters  1  have  endeavored  to  out- 
line the  story  of  the  achievements  of  our  century  in 
the  various  fields  of  pure  science.  In  so  broad  an  at- 
tempt, within  such  spacial  limits,  it  has  of  course  been 
impossible  to  dwell  upon  details,  or  even  to  hint  at 
every  minor  discovery.  At  best  one  could  but  sum- 
marize the  broad  sweep  of  progress  somewhat  as  a  bat- 
tle might  be  described  by  a  distant  eye-witness,  telling 
of  the  general  direction  of  action,"  of  the  movements 
•of  large  masses,  the  names  of  leaders  of  brigades  and 
divisions,  but  necessarily  ignoring  the  lesser  fluctuations 
of  advance  or  recession  and  the  individual  gallantry  of 
the  rank  and  file.  In  particular,  interest  has  centred 
upon  the  storming  of  the  various  special  strongholds  of 
ignorant  or  prejudiced  opposition,  which  at  last  have 
been  triumphantly  occupied  by  the  band  of  progress. 
In  each  case  where  such  a  stronghold  has  fallen,  the 
victory  has  been  achieved  solely  through  the  destructive 
agency  of  newly  discovered  or  newly  marshalled  facts 
—the  on\y  weapons  which  the  warrior  of  science  seeks 
or  cares  for.  Facts  must  be  marshalled,  of  course, 
about  the  guidon  of  a  hypothesis,  but  that  guidon  can 
only  lead  on  to  victory  if  the  facts  themselves  support 
2E  433 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

it.  Once  planted  victoriously  on  the  conquered  ram- 
parts, the  hypothesis  becomes  a  theory — a  generaliza- 
tion of  science — marking  a  fresh  coign  of  vantage,  which 
can  never  be  successfully  assailed  unless  by  a  new  host 
of  antagonistic  facts.  Such  generalizations,  with  the 
events  leading  directly  up  to  them,  have  chiefly  occu- 
pied our  attention. 

But  a  moment's  reflection  makes  it  clear  that  the  bat- 
tle of  science,  thus  considered,  is  ever  shifting  ground 
and  never  ended.  Thus  at  any  given  period  there  are 
many  unsettled  skirmishes  under  way ;  many  hypoth- 
eses are  yet  only  struggling  towards  the  strongholds  of 
theory,  perhaps  never  to  attain  it ;  in  many  directions 
the  hosts  of  antagonistic  facts  seem  so  evenly  matched 
that  the  hazard  of  war  appears  uncertain ;  or,  again,  so 
few  facts  are  available  that  as  yet  no  attack  worthy  the 
name  is  possible.  Such  unsettled  controversies  as  these 
have,  for  the  most  part,  been  ignored  in  our  survey  of 
the  field.  But  it  would  not  be  fair  to  conclude  our 
story  without  adverting  to  them,  at  least  in  brief ;  for 
some  of  them  have  to  do  with  the  most  comprehensive 
and  important  questions  with  which  science  deals,  and 
the  aggregate  number  of  facts  involved  in  these  unfin- 
ished battles  is  often  great,  even  though  as  yet  the 
marshalling  has  not  led  to  final  victory  for  any  faction. 
In  some  cases,  doubtless,  the  right  hypothesis  is  actually 
in  the  field,  but  its  supremacy  not  yet  conclusively 
proved — perhaps  not  to  be  proved  for  many  years  or 
decades  to  come.  Some  of  the  chief  scientific  results  of 
our  century  have  been  but  the  gaining  of  supremacy  for 
hypotheses  that  were  mere  forlorn  hopes,  looked  on 
with  general  contempt,  if  at  all  heeded,  when  the  eigh- 
teenth century  came  to  a  close — witness  the  doctrines  of 

434, 


SOME   UNSOLVED   SCIENTIFIC   PROBLEMS 

the  great  age  of  the  earth,  of  the  immateriality  of  heat, 
of  the  undulatory  character  of  light,  of  chemical  atom- 
icy,  of  organic  evolution.  Contrariwise,  the  opposite 
ideas  to  all  of  these  had  seemingly  a  safe  supremacy 
until  the  new  facts  drove  them  from  the  field.  Who 
shall  say,  then,  what  forlorn  hope  of  to-day's  science 
may  not  be  the  conquering  host  of  to-morrow?  All 
that  one  dare  attempt  is  to  cite  the  pretensions  of  a  few 
hypotheses  that  are  struggling  over  the  still  contested 
ground. 


SOLAR    AND    TELLURIC    PROBLEMS 

Our  sun  being  only  a  minor  atom  of  the  stellar  peb- 
ble, solar  problems  in  general  are  of  course  stellar  prob- 
lems also.  But  there  are  certain  special  questions  re- 
garding which  we  are  able  to  interrogate  the  sun  because 
of  his  proximity,  and  which  have,  furthermore,  a  pecul- 
iar interest  for  the  residents  of  our  little  globe  because 
of  our  dependence  upon  this  particular  star.  One  of  the 
most  far-reaching  of  these  is  as  to  where  the  sun  gets 
the  heat  that  he  gives  off  in  such  liberal  quantities.  We 
have  already  seen  that  Dr.  Mayer,  of  conservation-of- 
energy  fame,  was  the  first  to  ask  this  question.  As  soon 
as  the  doctrine  of  the  persistence  and  convertibility  of 
energy  was  grasped,  about  the  middle  of  the  century,  it 
became  clear  that  this  was  one  of  the  most  puzzling  of 
questions.  It  did  not  at  all  suffice  to  answer  that  the 
sun  is  a  ball  of  fire,  for  computation  showed  that,  at  the 
present  rate  of  heat-giving,  if  the  sun  were  a  solid  mass 
of  coal,  he  would  be  totally  consumed  in  about  five  thou- 
sand years.  As  no  such  decrease  in  size  as  this  implies 

435,- 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

had  taken  place  within  historic  times,  it  was  clear  that 
some  other  explanation  must  be  sought. 

Dr.  Mayer  himself  hit  upon  what  seemed  a  tenable 
solution  at  the  very  outset.  Starting  from  the  observed 
fact  that  myriads  of  tiny  meteorites  are  hurled  into  the 
earth's  atmosphere  daily,  he  argued  that  the  sun  must 
receive  these  visitants  in  really  enormous  quantities — 
sufficient,  probably,  to  maintain  his  temperature  at  the 
observed  limits.  There  was  nothing  at  all  unreasonable 
about  this  assumption,  for  the  amount  of  energy  in  a 
swiftly  moving  body  capable  of  being  transformed  into 
heat  if  the  body  be  arrested  is  relatively  enormous.  Thus 
it  is  calculated  that  a  pound  of  coal  dropped  into  the  sun 
from  the  mathematician's  favorite  starting-point,  infin- 
ity, would  produce  some  six  thousand  times  the  heat  it 
could  engender  if  merely  burned  at  the  sun's  surface. 
In  other  words,  if  a  little  over  two  pounds  of  material 
from  infinity  were  to  fall  into  each  square  yard  of  the 
sun's  surface  each  hour,  his  observed  heat  would  be  ac- 
counted for;  whereas  almost  seven  tons  per  square  yard 
of  stationary  fuel  would  be  required  each  hour  to  produce 
the  same  effect. 

In  view  of  the  pelting  which  our  little  earth  receives, 
it  seemed  not  an  excessive  requisition  upon  the  meteoric 
supply  to  suppose  that  the  requisite  amount  of  matter 
may  fall  into  the  sun,  and  for  a  time  this  explanation  of 
his  incandescence  was  pretty  generally  accepted.  But 
soon  astronomers  began  to  make  calculations  as  to  the 
amount  of  matter  which  this  assumption  added  to  our 
solar  system,  particularly  as  it  aggregated  near  the  sun 
in  the  converging  radii,  and  then  it  was  clear  that  no 
such  mass  of  matter  could  be  there  without  interfering 
demonstrably  with  the  observed  course  of  the  interior 

.436 


SOME    UNSOLVED   SCIENTIFIC   PROBLEMS 

planets.  So  another  source  of  the  sun's  energy  had  to 
be  sought.  It  was  found  forthwith  by  that  other  great 
German,  Helmholtz,  who  pointed  out  that  the  falling 
matter  through  which  heat  may  be  generated  might  just 
as  well  be  within  the  substance  of  the  sun  as  without ; 
in  other  words,  that  contraction  of  the  sun's  heated  body 
is  quite  sufficient  to  account  for  a  long-sustained  heat- 
supply  which  the  mere  burning  of  any  Known  substance 
could  not  approach.  Moreover,  the  amount  of  matter 
thus  falling  towards  the  sun's  centre  being  enormous — 
namely,  the  total  substance  of  the  sun — a  relatively  small 
amount  of  contraction  would  be  theoretically  sufficient 
to  keep  the  sun's  furnace  at  par,  so  to  speak. 

At  first  sight  this  explanation  seemed  a  little  puzzling 
to  many  laymen  and  some  experts,  for  it  seemed  to  im- 
ply, as  Lord  Kelvin  pointed  out,  that  the  sun  contracts 
because  it  is  getting  cooler,  and  gains  heat  because  it 
contracts.  But  this  feat  is  not  really  as  paradoxical  as 
it  seems,  for  it  is  not  implied  that  there  is  any  real  gain 
of  heat  in  the  sun's  mass  as  a  whole,  but  quite  the  reverse. 
All  that  is  sought  is  an  explanation  of  a  maintenance  of 
heat-giving  capacity  relatively  unchanged  for  a  long,  but 
not  an  interminable,  period.  Indeed,  exactly  here  comes 
in  the  novel  and  startling  feature  of  Helm  hoi  tz's  calcu- 
lation. According  to  Mayer's  meteoric  hypothesis,  there 
were  no  data  at  hand  for  any  estimate  whatever  as  to  the 
sun's  permanency,  since  no  one  could  surmise  what  might 
be  the  limits  of  the  meteoric  supply.  But  Helmholtz's 
estimate  implied  an  incandescent  body  cooling — keeping 
up  a  somewhat  equable  temperature  through  contraction 
for  a  time,  but  for  a  limited  time  only ;  destined  ulti- 
mately to  become  liquid,  solid ;  to  cool  below  the  tem- 
perature of  incandescence— to  die.  Not  only  so,  but  it 

437 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

became  possible  to  calculate  the  limits  of  time  within 
which  this  culmination  would  probably  occur.  It  was 
only  necessary  to  calculate  the  total  amount  of  heat 
which  could  be  generated  by  the  total  mass  of  our  solar 
system  in  falling  together  to  the  sun's  centre  from  "  in- 
finity" to  find  the  total  heat-supply  to  be  drawn  upon. 
Assuming,  then,  that  the  present  observed  rate  of  heat- 
giving  has  been  the  average  maintained  in  the  past,  a 
simple  division  gives  the  number  of  years  for  which  the 
original  supply  is  adequate.  The  supply  will  be  ex- 
hausted, it  will  be  observed,  when  the  mass  comes  into 
stable  equilibrium  as  a  solid  body,  no  longer  subject  to 
contraction,  about  the  sun's  centre — such  a  body,  in 
short,  as  our  earth  is  at  present. 

This  calculation  was  made  by  Lord  Kelvin,  Professor 
Tait,  and  others,  and  the  result  was  one  of  the  most  truly 
dynamitic  surprises  of  the  century.  For  it  transpired 
that,  according  to  mathematics,  the  entire  limit  of  the 
sun's  heat-giving  life  could  not  exceed  something  like 
twenty-five  millions  of  years.  The  publication  of  that 
estimate,  with  the  appearance  of  authority,  brought  a 
veritable  storm  about  the  heads  of  the  physicists.  The 
entire  geological  and  biological  worlds  were  up  in  arms 
in  a  trice.  Two  or  three  generations  before,  they  hurled 
brickbats  at  any  one  who  even  hinted  that  the  solar  sys- 
tem might  be  more  than  six  thousand  years  old  ;  now 
they  jeered  in  derision  at  the  attempt  to  limit  the  life- 
bearing  period  of  our  globe  to  a  paltry  fifteen  or  twenty 
millions. 

The  controversy  as  to  solar  time  thus  raised  proved 
one  of  the  most  curious  and  interesting  scientific  dispu- 
tations of  the  century.  The  scene  soon  shifted  from  the 
sun  to  the  earth ;  for  a  little  reflection  made  it  clear 

438 


SOME   UNSOLVED   SCIENTIFIC   PROBLEMS 

that  the  data  regarding  the  sun  alone  were  not  suffi- 
ciently definite.  Thus  Dr.  Croll  contended  that  if  the 
parent  bodies  of  the  sun  had  chanced  to  be  "  flying 
stars "  before  collision,  a  vastly  greater  supply  of  heat 
would  have  been  engendered  than  if  the  matter  merely 
fell  together.  Again,  it  could  not  be  overlooked  that  a 
host  of  meteors  are  falling  into  the  sun,  and  that  this 
source  of  energy,  though  not  in  itself  sufficient  to  ac- 
count for  all  the  heat  in  question,  might  be  sufficient  to 
vitiate  utterly  any  exact  calculations.  Yet  again,  Pro- 
fessor Lockyer  called  attention  to  another  source  of 
variation,  in  the  fact  that  the  chemical  combination  of 
elements  hitherto  existing  separately  must  produce  large 
quantities  of  heat,  it  being  even  suggested  that  this  source 
alone  might  possibly  account  for  all  the  present  output. 
On  the  whole,  then,  it  became  clear  that  the  contraction 
theory  of  the  sun's  heat  must  itself  await  the  demonstra- 
tion of  observed  shrinkage  of  the  solar  disc,  as  viewed  by 
future  generations  of  observers,  before  taking  rank  as  an 
incontestable  theory,  and  that  computations  as  to  time 
based  solely  on  this  hypothesis  must  in  the  meantime  be 
viewed  askance. 

But,  the  time  controversy  having  taken  root,  new 
methods  were  naturally  found  for  testing  it.  The  ge- 
ologists sought  to  estimate  the  period  of  time  that  must 
have  been  required  for  the  deposit  of  the  sedimentary 
rocks  now  observed  .to  make  up  the  outer  crust  of  the 
earth.  The  amount  of  sediment  carried  through  the 
mouth  of  a  great  river  furnishes  a  clew  to  the  rate  of 
denudation  of  the  area  drained  by  that  river.  Thus  the 
studies  of  Messrs.  Humphreys  and  Abbot,  made  for  a 
different  purpose,  show  that  the  average  level  of  the 
territory  drained  by  the  Mississippi  is  being  reduced  by 

439 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

about  one  foot  in  six  thousand  years.  The  sediment  is, 
of  course,  being  piled  up  out  in  the  Gulf  at  a  proportion- 
ate rate.  If,  then,  this  be  assumed  to  be  an  average  rate 
of  denudation  and  deposit  in  the  past,  and  if  the  total 
thickness  of  sedimentary  deposits  of  past  ages  were 
known,  a  simple  calculation  would  show  the  age  of  the 
earth's  crust  since  the  first  continents  were  formed. 
But  unfortunately  these  "ifs"  stand  mountain-high 
here,  all  the  essential  factors  being  indeterminate. 
Nevertheless,  the  geologists  contended  that  they  could 
easily  make  out  a  case  proving  that  the  constructive 
and  destructive  work  still  in  evidence,  to  say  nothing 
of  anterior  revolutions,  could  not  have  been  accom- 
plished in  less  than  from  twenty-five  to  fifty  millions  of 
years. 

This  computation  would  have  carried  little  weight 
with  the  physicists  had  it  not  chanced  that  another  com- 
putation of  their  own  was  soon  made  which  had  even 
more  startling  results.  This  computation,  made  by  Lord 
Kelvin,  was  based  on  the  rate  of  loss  of  heat  by  the 
earth.  It  thus  resembled  the  previous  solar  estimate  in 
method.  But  the  result  was  very  different,  for'the  new 
estimate  seemed  to  prove  that  since  the  final  crust  of 
the  earth  formed  a  period  of  from  one  hundred  to  two 
hundred  millions  of  years  has  efapsed. 

With  this  all  controversy  ceased,  for  the  most  grasp- 
ing geologist  or  biologist  would  content  himself  with  a 
fraction  of  that  time.  What  is  more  to  the  point,  how- 
ever, is  the  fact,  which  these  varying  estimates  have 
made  patent,  that  computations  of  the  age  of  the  earth 
based  on  any  data  at  hand  are  little  better  than  rough 
guesses.  Long  before  the  definite  estimates  were  under- 
taken, geologists  had  proved  that  the  earth  is  very,  very 

440 


SOME   UNSOLVED   SCIENTIFIC   PROBLEMS 

old,  and  it  can  hardly  be  said  that  the  attempted  com- 
putations have  added  much  of  definiteness  to  that  propo- 
sition. They  have,  indeed,  proved  that  the  period  of 
time  to  be  drawn  upon  is  not  infinite;  but  the  nebular 
hypothesis,  to  say  nothing  of  common-sense,  carried  us 
as  far  as  that  long  ago. 

If  the  computations  in  question  have  failed  of  their 
direct  purpose,  however,  they  have  been  by  no  means 
lacking  in  important  collateral  results.  To  mention  but 
one  of  these,  Lord  Kelvin  was  led  by  this  controversy 
over  the  earth's  age  to  make  his  famous  computation  in 
which  he  proved  that  the  telluric  structure,  as  a  whole, 
must  have  at  least  the  rigidity  of  steel  in  order  to  resist 
the  moon's  tidal  pull  as  it  does.  Hopkins  had,  indeed, 
made  a  somewhat  similar  estimate  as  early  as  1839, 
proving  that  the  earth's  crust  must  be  at  least  eight 
hundred  or  a  thousand  miles  in  thickness;  but  geologists 
had  utterly  ignored  this  computation,  and  the  idea  of  a 
thin  crust  on  a  fluid  interior  had,  continued  to  be  the 
orthodox  geological  doctrine.  Since  Lord  Kelvin's 
estimate  was  made,  his  claim  that  the  final  crust  of  the 
earth  could  not  have  formed  until  the  mass  was  solid 
throughout,  or  at  least  until  a  honeycomb  of  solid  matter 
had  been  bridged  up  from  centre  to  circumference,  has 
gained  pretty  general  acceptance.  It  still  remains  an 
open  question,  however,  as  to  what  proportion  the  lacunae 
of  molten  matter  bear  at  the  present  day  to  the  solidified 
portions,  and  therefore  to  what  extent  the  earth  will  be 
subject  to  further  shrinkage  and  attendant  surface 
contortions.  That  some  such  lacunas  do  exist  is  demon- 
strated daily  by  the  phenomena  of  volcanoes.  So,  after 
all,  the  crust  theory  has  been  supplanted  by  a  compro- 
mise theory  rather  than  completely  overthrown,  and 

441 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

our  knowledge  of  the  condition  of  the  telluric  depths  is 
still  far  from  definite. 

If  so  much  uncertainty  attends  these  fundamental 
questions  as  to  the  earth's  past  and  present,  it  is  not 
strange  that  open  problems  as  to  her  future  are  still 
more  numerous.  We  have  seen  how,  according  to  Pro- 
fessor Darwin's  computations,  the  moon  threatens  to 
come  back  to  earth  with  destructive  force  some  day. 
Yet  Professor  Darwin  himself  urges  that  there  are  ele- 
ments of  fallibility  in  the  data  involved  that  rob  the 
computation  of  all  certainty.  Much  the  same  thing  is 
true  of  perhaps  all  the  estimates  that  have  been  made 
as  to  the  earth's  ultimate  fate.  Thus  it  has  been  sug- 
gested that,  even  should  the  sun's  heat  not  forsake  us, 
our  day  will  become  month-long,  and  then  year-long; 
that  all  the  water  of  the  globe  must  ultimately  filter 
into  its  depths,  and  all  the  air  fly  off  into  space,  leaving 
our  earth  as  dry  and  as  devoid  of  atmosphere  as  the 
moon ;  and,  finally,  that  ether-friction,  if  it  exist,  or,  in 
default  of  that,  meteoric  friction,  must  ultimately  bring 
the  earth  back  to  the  sun.  But  in  all  these  prognosti- 
cations there  are  possible  compensating  factors  that 
vitiate  the  estimates  and  leave  the  exact  results  in 
doubt.  The  last  word  of  the  cosmic  science  of  our 
century  is  a  prophecy  of  evil — if  annihilation  be  an  evil. 
But  it  is  left  for  the  science  of  another  generation  to 
point  out  more  clearly  the  exact  terms  in  which  the 
prophecy  is  most  likely  to  be  fulfilled. 


SOME  UNSOLVED  SCIENTIFIC   PROBLEMS 
ii 

PHYSICAL    PROBLEMS 

In  regard  to  all  these  cosmic  and  telluric  problems, 
it  will  be  seen,  there  is  always  the  same  appeal  to  one 
central  rule  of  action — the  law  of  gravitation.  When 
\ve  turn  from  macrocosm  to  microcosm  it  would  appear 
as  if  new  forces  of  interaction  were  introduced  in  the 
powers  of  cohesion  and  of  chemical  action  of  molecules 
and  atoms.  But  Lord  Kelvin  has  argued  that  it  is  pos- 
sible to  form  such  a  conception  of  the  forms  and  space 
relations  of  the  ultimate  particles  of  matter  that  their 
mutual  attractions  may  be  explained  by  invoking  that 
same  law  of  gravitation  which  holds  the  stars  and  plan- 
ets in  their  course.  What,  then,  is  this  all-compassing 
power  of  gravitation  which  occupies  so  central  a  position 
in  the  scheme  of  mechanical  things? 

The  simple  answer  is  that  no  man  knows.  The  wisest 
physicist  of  to-day  will  assure  you  that  he  knows  abso- 
lutely nothing  of  the  why  of  gravitation — that  he  can 
no  more  explain  why  a  stone  tossed  into  the  air  falls 
back  to  earth  than  can  the  boy  who  tosses  the  stone. 
But  while  this  statement  puts  in  a  nutshell  the  scientific 
status  of  explanations  of  gravitation,  yet  it  is  not  in 
human  nature  that  speculative  scientists  should  refrain 
from  the  effort  to  explain  it.  Such  efforts  have  been 
made ;  yet,  on  the  whole,  they  are  surprisingly  few  in 
number ;  indeed,  there  are  but  two  that  need  claim  our 
attention  here,  and  one  of  these  has  hardly  more  than 
historical  interest.  One  of  these  is  the  so-called  ultra- 
mundane-corpuscle hypothesis  of  Le  Sage;  the  other  is. 
based  on  the  vortex  theory  of  matter. 

443 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

The  theory  of  Le  Sage  assumes  that  the  entire  uni- 
verse is  filled  with  infinitely  minute  particles  flving  in 
right  lines  in  every  direction  with  inconceivable  rapidity. 
Every  mass  of  tangible  matter  in  the  universe  is  inces- 
santly bombarded  by  these  particles,  but  any  two  non- 
contiguous masses  (whether  separated  by  an  infinitesi- 
mal space  or  by  the  limits  of  the  universe)  are  mutually 
shielded  by  one  another  from  a  certain  number  of  the 
particles,  and  thus  impelled  towards  one  another  bv  the 
excess  of  bombardment  on  their  opposite  sides.  What 
applies  to  two  masses  applies  also,  of  course,  to  any 
number  of  masses— in  short,  to  all  the  matter  in  the 
universe.  To  make  the  hypothesis  workable,  so  to  sav, 
it  is  necessary  to  assume  that  the  k' ultra-mundane"  par- 
ticles are  possessed  of  absolute  elasticity,  so  that  they 
rebound  from  one  another  on  collision  without  loss  of 
speed.  It  is  also  necessary  to  assume  that  all  tangible 
matter  has  to  an  almost  unthinkable  degree  a  sieve-like 
texture,  so  that  the  vast  proportion  of  the  coercive  par- 
ticles pass  entire!}7  through  the  body  of  any  mass  they 
encounter — a  star  or  world,  for  example — without  really 
touching  any  part  of  its  actual  substance.  This  assump- 
tion is  necessarv  because  gravitation  takes  no  account 

«/  O 

of  mere  corporeal  bulk,  but  only  of  mass  or  ultimate 
solidarity.  Thus  a  very  bulky  object  may  be  so  loosely 
meshed  that  it  retards  relatively  few  of  the  corpuscles, 
and  hence  gravitates  with  relative  feebleness  —  or,  to 
adopt  a  more  familiar  mode  of  expression,  is  light  in 
weight. 

This  is  certainly  heaping  hypotheses  together  in  a 
reckless  way,  and  it  is  perhaps  not  surprising  that  Le 
Sage's  conception  did  not  at  first  arouse  any  very  great 
amount  of  interest.  It  was  put  forward  about  a  century 

444 


SOME   UNSOLVED  SCIENTIFIC   PROBLEMS 

ago,  but  for  two  or  three  generations  remained  prac- 
tically unnoticed.  The  philosophers  of  the  first  half  of 
our  century  seem  to  have  despaired  of  explaining  gravi- 
tation, though  Faraday  long  experimented  in  the  hope 
of  establishing  a  relation  between  gravitation  and  elec- 
tricity or  magnetism.  But  not  long  after  the  middle  of 
the  century,  when  a  new  science  of  dynamics  was  claim- 
ing paramount  importance,- and  physicists  were  striving 
to  express  all  tangible  phenomena  in  terms  of  matter  in 
motion,  the  theory  of  Le  Sage  was  revived  and  given  a 
large  measure  of  attention.  It  had  at  least  the  merit  of 
explaining  the  facts  without  conflicting  with  any  known 
mechanical  law,  which  was  more  than  could  be  said  of 
any  other  guess  at  the  question  that  had  ever  been 
made. 

More  recently,  however,  another  explanation  has  been 
found  which  also  meets  this  condition.  It  is  a  concep- 
tion based,  like  most  other  physical  speculations  of  the 
last  generation,  upon  the  hypothesis  of  the  vortex  atom, 
and  was  suggested,  no  doubt,  by  those  speculations  which 
consider  electricity  and.  magnetism  to  be  conditions  of 
strain  or  twist  in  the  substance  of  the  universal  ether. 
In  a  word,  it  supposes  that  gravitation  also  is  a  form  of 
strain  in  this  ether — a  strain  that  may  be  likened  to  a 
suction  which  the  vortex  atom  is  supposed  to  exert  on 
the  ether  in  which  it  lies.  According  to  this  view,  gravi- 
tation is  not  a  push  from  without,  but  a  pull  from  within ; 
not  due  to  exterior  influences,  but  an  inherent  and  indis- 
soluble property  of  matter  itself.  The  conception  has 
the  further  merit  of  correlating  gravitation  with  elec- 
tricity, magnetism,  and  light,  as  a  conditjon  of  that 
strange  ethereal  ocean  of  which  modern  physics  takes 
so  much  account.  But  here,  again,  clearly,  we  are  but 

445 


THE  STORY  OF  NINETEENTH-CENTURY  SCIENCE 

heaping  hypothesis  upon  hypothesis,  as  before.  Still,  a 
hypothesis  that  violates  no  known  law  and  has  the  war- 
rant of  philosophical  probability  is  always  worthy  of  a 
hearing.  Only  we  must  not  forget  that  it  is  hypothesis 
only,  not  conclusive  theory. 

The  same  caution  applies,  manifestly,  to  all  the  other 
speculations  which  have  the  vortex  atom,  so  to  say,  for 
their  foundation-stone.  Thus  Professors  Stewart  and 
Tait's  inferences  as  to  the  destructibility  of  matter,  based 
on  the  supposition  that  the  ether  is  not  quite  frictionless, 
Professor  Dolbear's  suggestions  as  to  the  creation  of 
matter  through  the  development  of  new  ether  ripples, 
and  the  same  thinker's  speculations  as  to  an  upper  limit 
of  temperature,  based  on  the  mechanical  conception  of 
a  limit  to  the  possible  vibrations  of  a  vortex  ring,  not 
to  mention  other  more  or  less  fascinating  speculations 
based  on  the  vortex  hypothesis,  must  be  regarded,  what- 
ever their  intrinsic  interest,  as  insecurely  grounded,  until 
such  time  as  new  experimental  methods  shall  give  them 
another  footing.  Lord  Kelvin  himself  holds  all  such 
speculations  utterly  in  abeyance.  "  The  vortex  theory," 
he  says,  "  is  only  a  dream.  Itself  unproven,  it  can  prove 
nothing,  and  any  speculations  founded  upon  it  are  mere 
dreams  about  a  dream." 

That  certainly  must  be  considered  an  unduly  modest 
pronouncement  regarding  the  only  workable  hypothe- 
sis of  the  constitution  of  matter  that  has  ever  been 
imagined;  yet  the  fact  certainly  holds  that  the  vortex 
theory,  the  great  contribution  of  our  century  towards 
the  solution  of  a  world-old  problem,  has  not  been  car- 
ried beyond  the  stage  of  hypothesis,  and  must  be  passed 
on,  with  its  burden  of  interesting  corollaries,  to  another 
generation  for  the  experimental  evidence  that  will  lead 

446 


SOME   UNSOLVED   SCIENTIFIC   PROBLEMS 

to  its  acceptance  or  its  refutation.  Our  century  has 
given  experimental  proof  of  the  existence  of  the  atom, 
but  has  not  been  able  to  fathom  in  the  same  way  the 
exact  form  or  nature  of  this  ultimate  particle  of  matter. 
Equally  in  the  dark  are  we  as  to  the  explanation  of 
that  strange  affinity  for  its  neighbors  which  every  atom 
manifests  in  some  degree.  If  we  assume  that  the  power 
which  holds  one  atom  to  another  is  the  same  which  in 
case  of  larger  bodies  we  term  gravitation,  that  answer 
carries  us  but  a  little  way,  since,  as  we  have  seen,  gravi- 
tation itself  is  the  greatest  of  mysteries.  But  again,  how 
chances  it  that  different  atoms  attract  one  another  in  such 
varying  degrees,  so  that,  for  example,  fluorine  unites 
with  everything  it  touches,  argon  with  nothing?  And 
how  is  it  that  different  kinds  of  atoms  can  hold  to  them- 
selves such  varying  numbers  of  fellow-atoms — oxygen 
one,  hydrogen  two,  and  so  on  ?  These  are  questions  for 
the  future.  The  wisest  chemist  does  not  know  why  the 
simplest  chemical  experiment  results  as  it  does.  Take, 
for  example,  a  water-like  solution  of  nitrate  of  silver, 
and  let  fall  into  it  a  few  drops  of  another  water-like  solu- 
tion of  hydrochloric  acid;  a  white  insoluble  precipitate 
of  chloride  of  silver  is  formed.  Any  tyro  in  chemistry 
could  have  predicted  the  result  with  absolute  certainty. 
But  the  prediction  would  have  been  based  purely  upon 
previous  empirical  knowledge— solely  upon  the  fact  that 
the  thing  had  been  done  before  over  and  over,  always 
with  the  same  result.  Why  the  silver  forsook  the  ni- 
trogen atom,  and  grappled  the  atom  of  oxygen,  no  one 
knows.  Nor  can  any  one  as  yet  explain  just  why  it  is 
that  the  new  compound  is  an  insoluble,  colored,  opaque 
substance,  whereas  the  antecedent  ones  were  soluble, 
colorless,  and  transparent.  More  than  that,  no  one  can 

447 


TliE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

explain  with  certainty  just  what  is  meant  by  the  famil- 
iar word  soluble  itself.  That  is  to  say,  no  one  knows 
just  what  happens  when  one  drops  a  lump  of  salt  or 
sugar  into  a  bowl  of  water.  We  may  believe  with  Pro- 
fessor Ostwald  and  his  followers,  that  the  molecules  of 
sugar  merely  glide  everywhere  between  the  molecules  of 
water,  without  chemical  action ;  or,  on  the  other  hand, 
dismissing  this  mechanical  explanation,  we  may  say 
with  Mendeleef  that  the  process  of  solution  is  the  most 
active  of  chemical  phenomena,  involving  that  incessant 
interplay  of  atoms  known  as  dissociation.  But  these 
two  explanations  are  mutually  exclusive,  and  no  one  can 
say  positively  which  one,  if  either  one,  is  right.  Nor  is 
either  theory  at  best  more  than  a  half-explanation,  for 
the  why  of  the  strange  mechanical  or  chemical  activi- 
ties postulated  is  quite  ignored.  How  is  it,  for  example, 
that  the  molecules  of  water  are  able  to  loosen  the  inter- 
molecular  bonds  of  the  sugar  particles,  enabling  them  to 
scamper  apart  ? 

But,  for  that  matter,  what  is  the  nature  of  these  in- 
termolecular  bonds  in  any  case  ?  And  why,  at  the  same 
temperature,  are  some  substances  held  together  with 
such  enormous  rigidity,  others  so  loosely  ?  Why  does 
not  a  lump  of  iron  dissolve  as  readily  as  the  lump  of 
sugar  in  our  bowl  of  water?  Guesses  may  be  made  to- 
day at  these  riddles,  to  be  sure,  but  anything  like  tena- 
ble solutions  will  only  be  possible  when  we  know  much 
more  than  at  present  of  the  nature  of  intermolecular 
forces,  and  of  the  mechanism  of  molecular  structures. 
As  to  this  last,  studies  are  under  way  that  are  full  of 
promise.  For  the  past  ten  or  fifteen  years  Professor 
Yan  't  Hoof  of  Amsterdam  (now  of  Berlin),  with  a  com- 
pany of  followers,  has  made  the  space  relations  of  atoms 


SOME  UNSOLVED  SCIENTIFIC  PROBLEMS 

a  special  study,  with  the  result  that  so-called  stereo- 
chemistry has  attained  a  firm  position.  A  truly  amaz- 
ing insight  has  been  gained  into  the  space  relations  of 
the  molecules  of  carbon  compounds  in  particular,  and 
other  compounds  are  under  investigation.  But  these  re- 
sults, wonderful  though  they  seem  when  the  intricacy 
of  the  subject  is  considered,  are,  after  all,  only  tenta- 
tive. It  is  demonstrated  that  some  molecules  have  their 
atoms  arranged  in  perfectly  definite  and  unalterable 
schemes,  but  just  how  these  systems  are  to  be  mechani- 
cally pictured— whether  as  miniature  planetary  systems 
or  what  not — remains  for  the  investigators  of  the  future 
to  determine. 

It  appears,  then,  that  whichever  way  one  turns  in  the 
realm  of  the  atom  and  molecule,  one  finds  it  a  land  of 
mysteries.  In  no  field  of  science  have  more  startling 
discoveries  been  made  in  our  century  than  here;  yet 
nowhere  else  do  there  seem  to  lie  wider  realms  yet  un- 
fathomed. 

in 

LIFE    PROBLEMS 

In  the  life  history  of  at  least  one  of  the  myriad  star 
systems  there  has  come  a  time  when,  on  the  surface  of 
one  of  the  minor  members  of  the  group,  atoms  of  mat- 
ter have  been  aggregated  into  such  associations  as  to 
constitute  what  is  called  living  matter.  A  question 
that  at  once  suggests  itself  to  any  one  who  conceives 
even  vaguely  the  relative  uniformity  of  conditions  in 
the  different  star  groups  is  as  to  whether  other  worlds 
than  ours  have  also  their  complement  of  living  forms. 
The  question  has  interested  speculative  science  more 
2v  449 


THE   STORY  OF  NINETEENTH-CENTURY   SCIENCE 

perhaps  in  our  century  than  ever  before,  but  it  can 
hardly  be'  said  that  much  progress  has  been  made  tow- 
ards a  definite  answer.  At  first  blush  the  demonstration 
that  all  the  worlds  known  to  us  are  composed  of  the 
same  matter,  subject  to  the  same  general  laws,  and 
probably  passing  through  kindred  stages  of  evolution 
and  decay,  would  seem  to  carry  with  it  the  reasonable 
presumption  that  to  all  primary  planets,  such  as  ours,  a 
similar  life-bearing  stage  must  come.  But  a  moment's 
reflection  shows  that  scientific  probabilities  do  not  carry 
one  safely  so  far  as  this.  Living  matter,  as  we  know  it, 
notwithstanding  its  capacity  for  variation,  is  condi- 
tioned within  very  narrow  limits  as  to  physical  sur- 
roundings. Now  it  is  easily  to  be  conceived  that  these 
peculiar  conditions  have  never  been  duplicated  on  any 
other  of  all  the  myriad  worlds.  If  not,  then  those  more 
complex  aggregations  of  atoms  which  we  must  suppose 
to  have  been  built  up  in  some  degree  on  all  cooling 
globes  must  be  of  a  character  so  different  from  what  we 
term  living  matter  that  we  should  not  recognize  them  as 
such.  Some  of  them  may  be  infinitely  more  complex, 
more  diversified  in  their  capacities,  more  widely  re- 
sponsive to  the  influences  about  them,  than  any  living 
thing  on  our  earth,  and  yet  not  respond  at  all  to  the 
conditions  which  we  apply  as  tests  of  the  existence  of 
life. 

This  is  but  another  way  of  saying  that  the  peculiar 
limitations  of  specialized  aggregations  of  matter  which 
characterize  what  we  term  living  matter  may  be  mere 
incidental  details  of  the  evolution  of  our  particular  star 
group,  our  particular  planet  even — having  some  such 
relative  magnitude  in  the  cosmic  order  as,  for  example, 
the  exact  detail  of  outline  of  some  particular  leaf  of  a 

450 


SOME  UNSOLVED  SCIENTIFIC   PROBLEMS 

tree  bears  to  the  entire  subject  of  vegetable  life.  But, 
on  the  other  hand,  it  is  also  conceivable  that  the  condi- 
tions on  all  planets  comparable  in  position  to  ours, 
though  never  absolutely  identical,  yet  pass  at  some  stage 
through  so  similar  an  epoch  that  on  each  and  every  one' 
of  them  there  is  developed  something  measurably  com- 
parable, in  human  terms,  to  what  we  here  know  as  liv- 
ing matter;  differing  widely,  perhaps,  from  any  partic- 
ular form  of  living  being  here,  yet  still  conforming 
broadly  to  a  definition  of  living  things.  In  that  case 
the  life-bearing  stage  of  a  planet  must  be  considered  as 
having  far  more  general  significance ;  perhaps  even  as 
constituting  the  time  of  fruitage  of  the  cosmic  organ- 
ism, though  nothing  but  human  egotism  gives  warrant  to 
this  particular  presumption. 

Between  these  two  opposing  views  every  oYie  is  free 
to  choose  according  to  his  preconceptions,  for  as  yet 
science  is  unable  to  give  a  deciding  vote.  Equally  open 
to  discussion  is  that  other  question,  as  to  whether  the 
evolution  of  universal  atoms  into  a  "vital"  association 
occurred  but  once  on  our  globe,  forming  the  primitive 
mass  from  which  all  the  diversified  forms  evolved,  or 
whether  such  shifting  from  the  so-called  non-vital  to  the 
vital  was  many  times  repeated— perhaps  still  goes  on  in- 
cessantly. It  is  quite  true  that  the  testimony  of  our 
century,  so  far  as  it  goes,  is  all  against  the  idea  of 
"  spontaneous  generation  "  under  existing  conditions.  It 
has  been  clearly  enough  demonstrated  that  the  bacteria 
and  other  low  forms  of  familiar  life  which  formerly  were 
supposed  to  originate  "spontaneously"  had  a  quite  dif- 
ferent origin.  But  the  solution  of  this  special  case  leaves 
the  general  problem  still  far  from  solved.  Who  knows 
what  are  the  conditions  necessary  to  the  evolution  of  the 

451 


THE   STORY  OF  NINETEENTH-CENTURY  SCIENCE 

ever-present  atoms  into  "  vital "  associations  ?  Perhaps 
extreme  pressure  may  be  one  of  these  conditions  ;  and, 
for  aught  any  man  knows  to  the  contrary,  the  "spon- 
taneous generation  "  of  living  protoplasm  may  be  taking 
place  incessantly  at  the  bottom  of  every  ocean  of  the 
globe. 

This  of  course  is  a  mere  bald  statement  of  possibilities. 
It  may  be  met  by  another  statement  of  possibilities,  to 
the  effect  that  perhaps  the  conditions  necessary  to  the 
evolution  of  living  matter  here  may  have  been  fulfilled 
but  once,  since  which  time  the  entire  current  of  life  on 
our  globe  has  been  a  diversified  stream  from  that  one 
source.  Observe,  please,  that  this  assumption  does  not 
fall  within  that  category  which  I  mention  above  as  con- 
traband of  science  in  speaking  of  the  origin  of  worlds. 
The  existence  of  life  on  our  globe  is  only  an  incident 
limited  to  a  relatively  insignificant  period  of  time,  and 
whether  the  exact  conditions  necessary  to  its  evolution 
pertained  but  one  second  or  a  hundred  million  years  does 
not  in  the  least  matter  in  a  philosophical  analysis.  It  is 
merely  a  question  of  fact,  just  as  the  particular  temper- 
ature of  the  earth's  surface  at  any  given  epoch  is  a  ques- 
tion of  fact,  the  one  condition,  like  the  other,  being  tem- 
porary and  incidental.  But,  as  I  have  said,  the  question 
of  fact  as  to  the  exact  time  of  origin  of  life  on  our  globe 
is  a  question  science  as  yet  cannot  answer. 

But,  in  any  event,  what  is  vastly  more  important  than 
this  question  as  to  the  duration  of  time  in  which  living 
matter  was  evolved  is  a  comprehension  of  the  philosophi- 
cal status  of  this  evolution  from  the  "non-vital"  to  the 
"  vital."  If  one  assumes  that  this  evolution  was  brought 
about  by  an  interruption  of  the  play  of  forces  hitherto 
working  in  the  universe — that  the  correlation  of  forces 

453 


SOME  UNSOLVED  SCIENTIFIC  PROBLEMS 

involved  was  unique,  acting  then  and  then  only — by  that 
assumption  he  removes  the  question  of  the  origin  of  life 
utterly  from  the  domain  of  science — exactly  as  the  as- 
sumption of  an  initial  push  would  remove  the  question 
of  the  origin  of  worlds  from  the  domain  of  science.  But 
the  science  of  to-day  most  emphatically  denlurs  to  any 
such  assumption.  Every  scientist  with  a  wide  grasp  of 
facts,  who  can  think  clearly  and  without  prejudice  over 
the  field  of  what  is  known  of  cosmic  evolution,  must  be 
driven  to  believe  that  the  alleged  wide  gap  between 
vital  and  non-vital  matter  is  largely  a  figment  of  prej- 
udiced human  understanding.  In  the  broader  view  there 
seem  no  gaps  in  the  scheme  of  cosmic  evolution — no 
break  in  the  incessant  reciprocity  of  atomic  actions, 
whether  those  atoms  be  floating  as  a  "fire  mist"  out  in 
one  part  of  space,  or  aggregated  into  the  brain  of  a  man 
in  another  part.  And  it  seems  well  within  the  range  of 
scientific  expectation  that  the  laboratory  worker  of  the 
future  will  learn  how  so  to  duplicate  telluric  conditions 
that  the  play  of  universal  forces  will  build  living  matter 
out  of  the  inorganic  in  the  laboratory,  as  they  have  done, 
and  perhaps  still  are  doing,  in  the  terrestrial  oceans. 

To  the  timid  reasoner  that  assumption  of  possibilities 
may  seem  startling.  But  assuredly  it  is  no  more  so  than 
seemed,  a  century  ago,  the  assumption  that  man  has 
evolved,  through  the  agency  of  "natural  laws"  only, 
from  the  lowest  organism.  Yet  the  timidity  of  that 
elder  day  has  been  obliged  by  the  progress  of  our  cen- 
tury to  adapt  its  conceptions  to  that  assured  sequence 
of  events.  And  some  day,  in  all  probability,  the  timid- 
ity of  to-day  will  be  obliged  to  take  that  final  logical 
step  which  to-day's  knowledge  foreshadows  as  a  future 
if  not  a  present  necessity. 

453 


THE  STORY   OF  NINETEENTH-CENTURY   SCIENCE 

Whatever  future  science  may  be  able  to  accomplish  in 
this  direction,  however,  it  must  be  admitted  that  present 
science  finds  its  hands  quite  full,  without  going  farther 
afield  than  to  observe  the  succession  of  generations 
among  existing  forms  of  life.  Since  the  establishment 
of  the  doctrine  of  organic  evolution,  questions  of  hered- 
ity, always  sufficiently  interesting,  have  been  at  the  very 
focus  of  attention  of  the  biological  world.  These  ques- 
tions, under  modern  treatment,  have  resolved  them- 
selves, since  the  mechanism  of  such  transmission  has 
been  proximately  understood,  into  problems  of  cellular 
activity.  And  much  as  has  been  learned  about  the  cell 
of  late,  that  interesting  microcosm  still  offers  a  multi- 
tude of  intricacies  for  solution. 

Thus,  at  the  very  threshold,  some  of  the  most  element- 
ary principles  of  mechanical  construction  of  the  cell  are 
still  matters  of  controversy.  On  the  one  hand,  it  is  held 
by  Professor  O.  Biitschli  and  his  followers  that  the  sub- 
stance of  the  typical  cell  is  essentially  alveolar,  or  foam- 
like,  comparable  to  an  emulsion,  and  that  the  observed 
reticular  structure  of  the  cell  is  due  to  the  intersections 
of  the  walls  of  the  minute  ultimate  globules.  But  an- 
other equally  authoritative  school  of  workers  holds  to 
the  view,  first  expressed  by  Frommann  and  Arnold, 
that  the  reticulum  is  really  a  system  of  threads,  which 
constitute  the  most  important  basis  of  the  cell  structure. 
It  is  even  held  that  these  fibres  penetrate  the  cell  walls 
and  connect  adjoining  cells,  so  that  the  entire  body  is  a 
reticulum.  For  the  moment  there  is  no  final  decision 
between  these  opposing  views.  Professor  Wilson  of 
Columbia  has  suggested  that  both  may  contain  a  meas- 
ure of  the  truth. 

Again,  it  is  a  question  whether  the  finer  granules  seen 

454 


SOME   UNSOLVED   SCIENTIFIC   PROBLEMS 

within  the  cell  are  or  are  not  typical  structures,  "  capa- 
ble of  assimilation,  growth,  and  division,  and  hence  to 
be  regarded  as  elementary  units  of  structure  standing 
between  the  cell  and  the  ultimate  molecules  of  living 
matter."  The  more  philosophical  thinkers,  like  Spencer, 
Darwin,  Haeckel,  Michael  Foster,  August  Weismann, 
and  many  others,  believe  that  such  "intermediate  units 
must  exist,  whether  or  not  the  microscope  reveals  them 
to  view.  Weismann,  who  has  most  fully  elaborated  a 
hypothetical  scheme  of  the  relations  of  the  intracellular 
units,  identifies  the  larger  of  these  units  not  with  the 
ordinary  granules  of  the  cell,  but  with  a  remarkable 
structure  called  chromatin,  which  becomes  aggregated 
within  the  cell  nucleus  at  the  time  of  cellular  division— 
a  structure  which  divides  into  definite  parts,  and  goes 
through  some  most  suggestive  manoeuvres  in  the 
process  of  cell  multiplication.  All  these  are  puzzling 
structures;  and  there  is  another  minute  body  within 
the  cell,  called  the  centrosome,  that  is  quite  as  much 
so.  This  structure,  discovered  by  Van  Beneden,  has 
been  regarded  as  essential  to  cell  division,  yet  some 
recent  botanical  studies  seem  to  show  that  sometimes 
it  is  altogether  wanting  in  a  dividing  cell. 

In  a  word,  the  architecture  of  the  cell  has  been  shown 
by  modern  researches  to  be  wonderfully  complicated,  but 
the  accumulating  researches  are  just  at  a  point  where 
much  is  obscure  about  many  of  the  observed  phenomena. 
The  immediate  future  seems  full  of  promise  of  advances 
upon  present  understanding  of  cell  processes.  But  for 
the  moment  it  remains  for  us,  as  for  preceding  genera- 
tions, about  the  most  incomprehensible,  scientifically 
speaking,  of  observed  phenomena,  that  a  single  micro- 
scopic egg  cell  should  contain  within  its  substance  all 

455 


THE   STORY   OF   NINETEENTH-CENTURY   SCIENCE 

the  potentialities  of  a  highly  differentiated  adult  being. 
The  fact  that  it  does  contain  such  potentialities  is  the 
most  familiar  of  e very-day  biological  observations,  but 
not  even  a  proximal  explanation  of  the  fact  is  as  yet 
attainable. 

Turning  from  the  cell  as  an  individual  to  the  mature 
organism  which  the  cell  composes  when  aggregated 
with  its  fellows,  one  finds  the  usual  complement  of  open 
questions,  of  greater  or  less  significance,  focalizing  the 
attention  of  working  biologists.  Thus  the  evolutionist, 
secure  as  is  his  general  position,  is  yet  in  doubt  when 
it  comes  to  tracing  the  exact  lineage  of  various  forms. 
He  does  not  know,  for  example,  exactly  which  order 
of  invertebrates  contains  the  type  from  which  verte- 
brates sprang,  though  several  hotly  contested  opin- 
ions, each  exclusive  of  the  rest,  are  in  the  field.  Again, 
there  is  like  uncertainty  and  difference  of  opinion 
as  to  just  which  order  of  lower  vertebrates  formed 
the  direct  ancestry  of  the  mammals.  Among  the  mam- 
mals themselves  there  are  several  orders,  such  as  the 
whales,  the  elephants,  and  even  man  himself,  whose  ex- 
act lines  of  more  immediate  ancestry  are  not  as  fully 
revealed  by  present  paleontology  as  is  to  be  fully 
desired. 

All  these,  however,  are  details  that  hardly  take  rank 
with  the  general  problems  that  we  are  noticing.  There 
are  other  questions,  however,  concerning  the  history 
and  present  evolution  of  man  himself,  that  are  of  wider 
scope,  or  at  least  of  seemingly  greater  importance  from 
a  human  stand-point,  which  within  recent  decades  have 
come  for  the  first  time  within  the  scope  of  truly  induc- 
tive science.  These  are  the  problems  of  anthropology 
—a  science  of  such  wide  scope,  such  far-reaching  col- 

456 


SOME  UNSOLVED   SCIENTIFIC  PROBLEMS 

lateral  implications,  that  as  yet  its  specific  field  and 
functions  are  not  as  clearly  defined  or  as  generally  rec- 
ognized as  they  are  probably  destined  to  be  in  the  near 
future.  The  province  of  this  new  science  is  to  correlate 
the  discoveries  of  a  wide  range  of  collateral  sciences — 
paleontology,  biology,  medicine,  and  so  on — from  the 
point  of  view  of  human  history  and  human  welfare. 
To  this  end  all  observable  races  of  men  are  studied  as 
to  their  physical  characteristics,  their  mental  and  moral 
traits^  their  manners,  customs,  languages,  and  religions. 
A  mass  of  data  is  already  at  hand,  and  in  process  of 
sorting  and  correlating.  Out  of  this  effort  will  probably 
come  all  manner  of  useful  generalizations,  perhaps  in 
time  bringing  sociolog}^  or  the  study  of  human  social 
relations,  to  the  rank  of  a  veritable  science.  But  great 
as  is  the  promise  of  anthropology,  it  can  hardly  be  de- 
nied that  the  broader  questions  with  which  it  has  to 
deal — questions  of  race,  of  government,  of  social  evolu- 
tion— are  still  this  side  the  fixed  plane  of  assured  gener- 
alization. No  small  part  of  its  interest  and  importance 
depends  upon  the  fact  that  the  great  problems  that 
engage  it  are  as  yet  unsolved  problems.  In  a  word, 
anthropology  is  perhaps  the  most  important  science  in 
the  hierarchy  to-day  exactly  because  it  is  an  immature 
science.  Its  position  to-day  is  perhaps  not  unlike  that 
of  paleontology  at  the  close  of  the  eighteenth  century. 
May  its  promise  find  as  full  fruition ! 


INDEX 


ADAMS,  JOHN,  his  determination  of 
the  exact  location  of  Neptune,  48  ; 
corrects  Laplace  in  reference  to  the 
moon's  acceleration,  51. 

Adams,  Professor,  his  investigation 
of  meteor  showers,  59. 

Aerial  currents,  their  classification 
and  the  laws  governing  them,  182— 
191. 

Aerolites,  study  of  their  origin  and 
character,  157-162. 

Agassiz,  Jean  Louis  Rodolphe,  his 
belief  in  the  special-creation  hy- 
pothesis, 105  ;  his  advocacy  and  es- 
tablishment of  the  glacial  theory, 
134-136;  on  the  reception  of  sci- 
entific truth,  153. 

Alibert,  Jean  Louis,  makes  known 
the  cause  and  cure  of  the  itch,  362. 

Alpha  Centauri,  its  comparative  dis- 
tance from  tiie  earth,  66. 

Amici,  Giovanni  Battista,  his  inven- 
tion of  the  reflecting  microscope, 
327,  328. 

Ampere,  Andre  Marie,  establishes  the 
connection  of  magnetism  and  elec- 
tricity, 207 ;  confirms  the  atomic 
theory  of  Avogadro,  258  ;  discovers 
the  properties  of  ammonium,  267. 

Anaesthesia,  discovery  of  the  method 
of,  365-375. 

Anatomy,  eighteenth -century  prog- 
ress in  the  science,  36.  See  Anat- 
omy and  physiology. 

Anatomy  and  physiology,  their  prog- 
ress in  the  nineteenth  century, 
321-353  ;  Cuvier's  classification  of 
the  animal  kingdom  and  his  "law 
of  co-ordination,"  321,  322;  Bi- 
chat's  generalization  of  the  animal 


organs,  322,  323 ;  and  his  division 
of  all  animal  structures  into  tis- 
sues, 324  ;  improvements  in  micro- 
scopes and  lenses,  and  the  inven- 
tion of  the  compound  microscope, 
324-328  ;  rise  of  histology  and  its 
triumphs,  328-336 ;  establishment 
and  development  of  the  cell  theory, 
336-346 ;  investigations  of  the  proc- 
esses of  digestion  and  respiration 
and  of  the  functions  of  the  human 
organs,  346-353. 

Anthrax,  discovery  of  its  cause  and 
remedy,  380,  381,  387-389. 

Anthropology,  its  far-reaching  pos- 
sibilities and  its  unsolved  prob- 
lems, 456,  457. 

Anti-cyclone,  description  of,  190. 

Antisepsis,  the  theory  and  practice 
of,  382-386. 

Antitoxine,  its  discovery  and  appli- 
cation, 390-392. 

Anti-trade-winds,  their  cause  and 
effects,  178,  185,  186. 

Arago,  Dominique  Francois,  his  pio- 
neer work  in  celestial  photography, 
76  ;  champions  Fresnel's  undulatory 
theory  of  light  and  the  feud  which 
his  advocacy  engendered,  202-204, 
225  ;  discovers  that  magnets  may  be 
produced  by  electrical  induction, 208. 

Arcturus,  its  comparative  brightness, 
69. 

Asteroids,  their  discovery  and  theo- 
ries regarding,  44-48. 

Astronomy,  its  development  during 
the  eighteenth  century,  5-17;  the 
"  nebular  hypothesis,"  its  amplifi- 
cation and  completion,  13-17;  prog- 
ress of  the  science  during  the 


459 


INDEX 


nineteenth  century,  44-87 ;  dis- 
covery of  Ceres,  by  Piazzi,  44 ;  of 
Pallas  and  Vesta,  by  Gibers,  44, 
47;  and  of  Juno,  by  Harding,  "47  ; 
Hencke's  discovery  of  a  fifth  as- 
teroid is  followed  by  a  thorough 
investigation  of  the  asteroidal  sys- 
tem, 47 ;  how  the  asteroids  are 
accounted  for,  47,  48 ;  discovery  of 
Neptune,  predicated  by  Bessel  and 
Leverrier,  is  accomplished  by  Dr. 
Galle,  48,  49  ;  Leverrier's  predica- 
tion of  a  trans-Neptunian  planet, 
49 ;  discovery  of  the  moons  of 
Mars  by  Professor  Hall,  49 ;  dis- 
covery of  Saturn's  crape  ring,  49, 
50 ;  Saturn's  rings  discussed  and 
their  nature  determined,  50 ;  theo- 
ries regarding  the  acceleration  of 
the  moon,  and  how  it  is  accounted 
for,  50-53  ;  speculations  regarding 
comets  and  the  discovery  of  their 
nature  and  constituents,  53-60  ;  the 
study  of  double  stars  by  William 
and  John  Herschel  and  others, 
63-65  ;  star  distance  determined, 
65-69 ;  and  star  motion,  mass,  and 
brightness  reckoned,  69,  70  ;  solar 
and  sidereal  investigations  by 
means  of  the  spectroscope,  70-76  ; 
discovery  of  "  invisible "  or  dark 
stars,  74-76  ;  triumphs  of  celestial 
photography,  76-83,  285,  286; 
Lockyer's  "  meteoric  hypothesis," 
83-86  ;  speculations  as  to  the  po- 
tentialities of  the  stellar  universe, 
86,  87 ;  some  unsolved  solar  and 
telluric  problems,  435-442. 

Atomic  theory,  discovery  and  devel- 
opment of,  252-262. 

Atoms,  Boscovich's  speculations  re- 
garding, 241  ;  their  combining 
weights  determined  and  the  method 
of  expressing  them  invented,  254, 
255,  259,  260 ;  law  of  the  specific 
heat  of,  260-262  ;  establishment  of 
the  law  of  valency,  269-275  ;  their 
character  and  properties  investi- 
gated, 275-278 ;  Prout's  theory  of 
the  atomic  weights  and  compound 
nature  of  the  elements,  278-280, 
283-287;  some  unsolved  problems 
regarding,  447-449. 


Auenbrugger  von  Auenbrog,  his  in- 
vention of  the  percussion  method 
for  studying  disease,  355. 

Aurora,  the,  speculations  regarding 
cause  of,  162-167. 

Auscultation,  its  discovery  and  de- 
velopment as  an  aid  to  diagnosis, 
356,  359. 

Avogadro,  Amadeo,  his  hypothesis  as 
to  the  numbers  of  ultimate  par- 
ticles in  volumes  of  gases,  and  his 
invention  of  the  term  "  molecule  " 
as  the  unit  of  physical  structure, 
258,  269. 

BACTERIA,  investigations  relating  to, 
379-386. 

Baer,  Karl  Ernst  von,  his  anatomi- 
cal researches,  337. 

Bary,  Heinrich  Anton  de,  his  dis- 
covery of  the  identity  of  the  ani- 
mal and  vegetable  cell,  340. 

Bastian,  Henry  Charlton,  revives 
Pouchet's  theory  of  "  spontaneous 
generation,"  320. 

Beaumont,  Elie  de,  his  contention  as 
•  to  the  origin  of  mountains,  130,  145. 

Behring,  Dr.,  his  discoveries  in  serum- 
therapy,  392. 

Bell,  Sir  Charles,  his  epochal  psy- 
chological discovery,  401,  402. 

Bernard,  Claude,  his  study  of  the 
pancreas,  347  ;  his  discovery  of  the 
glycogenic  function  of  the  liver, 
351,  352;  his  discoveries  relating 
to  the  nervous  system,  405,  406. 

Bernoulli,  Daniel,  originator  of  the 
kinetic  theory  of  gases,  242,  243. 

Berthollet,  Claude  Louis,  aids  in 
the  development  of  a  new  chemistry, 
32 ;  his  theory  of  chemical  com- 
bination, 255. 

Berzelius,  Johan  Jacob,  confirms 
and  advocates  Dalton's  atomic  the- 
ory, 256,  259 ;  his  extension  of  the 
binary  theory  and  establishment  of 
theoretical  chemistry,  264,  265,  267, 
268. 

Bessel,  Friedrich  Wilhelm,  predicts 
the  existence  of  a  trans-Uranian 
planet,  48  ;  his  successful  measure- 
ment of  the  parallax  of  a  star,  66  ; 
his  discovery  of  "  invisible"  stars,  74. 


INDEX 


Bichat,  Marie  Frangois  Xavier,  his 
generalization  of  the  animal  organs, 
322,  323;  his  classification  of  all 
animal  structures  into  tissues,  324. 

Biela,  Wilhelm  von,  his  discovery  of 
the  comet  bearing  his  name,  58 ; 
and  its  after  career  and  destruc- 
tion, 58,  59. 

Binary  composition  of  all  chemical 
compounds,  theory  of,  262-265. 

Biology,  the  great  advances  in  the 
science  made  possible  through 
eighteenth-century  explorations,  35, 
36 ;  its  progress  during  the  nine- 
teenth century, 288-320;  eighteenth- 
century  theories  of  organic  evolu- 
tion, 288-293  ;  Lamarck's  theory 
of  the  transmutation  of  species, 
293-297;  Cuvier's  theory  of  special 
creation  and  fixity  of  species,  297- 
302  ;  Oken's  theory  of  "  sponta- 
neous generation  "  and  of  evolution 
of  species,  298,  320;  Darwin's 
theory  of  the  origin  of  species  by 
natural  selection,  or  the  "survival 
of  the  fittest,"  302-310;  triumph 
of  Darwin's  theory  and  how  it  was 
effected,  310-317;  theories  regard- 
ing the  "origin  of  the  fittest," 
317-319  ;  consideration  of  the  next 
step  in  organic  evolution,  320. 

Biot,  Jean  Baptiste,  his  investigation 
of  the  L'Aigle  aerolite,  158;  op- 
poses the  undulatory  theory  of  light, 
203,  223. 

Black,  Joseph,  discoverer  of  latent 
heat,  34,  171. 

Blood,  the,  discoveries  relating  to, 
329,  349,  350. 

Boerhaave,  Hermann,  his  theory  of 
the  respiratory  function,  39. 

Boillard,  Dr.,  his  researches  in  cere- 
bral physiology,  419. 

Bois-Reymond,  Ernil  du,  his  psycho- 
physiological  researches,  408. 

Bond,  William  C.,  his  discovery  of 
Saturn's  inner  ring,  49. 

Boscovich,  Ruggiero  Giuseppe,  his 
speculation  as  to  the  ultimate  con- 
stitution of  matter,  241. 

Braid,  James,  his  investigation  of 
hypnotism,  415. 

Brain,  the,  Cabanis's  conception    of 


the  action  and  functions  of,  414, 
415.  See  Psychology. 

Bredichin's  cometary  theory,  54,  55. 

Brewster,  Sir  David,  refuses  to  accept 
the  theory  of  the  conservation  of 
energy,  218;  his  suggested  im- 
provement of  lenses,  325,  326. 

Broca,  Paul,  his  discovery  of  cerebral 
localization,  419,  422.  " 

Brodie,  Sir  Benjamin,  his  untimely  pre- 
diction regarding  anaesthetics,  366. 

Brongniart,  Alexandre,  how  he  ac- 
counted for  the  bowlders  on  the 
Jura,  131;  his  study  of  strata 
around  Paris,  138. 

Brontotheridce,  or  Titanotlieres,  their 
line  of  descent,  121. 

Brown,  Robert,  his  discovery  of  the  nu- 
cleus of  the  vegetable  cell,  330,  331. 

Brown-Sequard,  Charles  Edouard,  his 
investigations  of  the  nervous  sys- 
tem, 405. 

Bruno,  Giordano,  believed  some  of 
the  planets  inhabited,  12;  burned 
at  the  stake  for  teaching  that  our 
earth  is  not  the  centre  of  the  uni- 
verse, 16. 

Buch,  Leopold  von,  his  conception  of 
the  origin  of  mountains  and  of  the 
erratic  bowlders  on  the  Jura,  130  ; 
dissents  from  the  doctrine  of  special 
creation,  301. 

Buckland,  William,  his  discovery  of 
fossil  bones  at  Kirkdale,  Yorkshire, 
and  his  deductions  therefrom,  95 ; 
how  he  accounted  for  the  bowlders 
on  the  Jura,  131 ;  adopts  the  glacial 
theory,  135. 

Buffon,  Comte  de  (Georges  Louis  Le- 
clerc),  his  early  advocacy  of  the 
theory  of  transmutation  of  species, 
291,  292,  318. 

Bunsen,  Robert  Wilhelm,  with  the 
assistance  of  Kirchhoff,  perfects  the 
spectroscope,  70,  283. 

Burnham,  S.  W.,  his  enthusiastic 
search  for  double  stars,  65. 

Butschli,  Professor,  his  theory  of  cell 
formation,  454. 

CABANIS,  PIERRE  JEAN  GKORGE,  his 
conception  of  the  action  and  func- 
tions of  the  brain,  414,  415. 


461 


INDEX 


Carnot,  Sadi,  discovers  that  heat  and 
mechanical  work  are  mutually  con- 
vertible, 213. 

Carpenter,  William  Benjamin,  his 
theory  of  oceanic  circulation,  180; 
his  advocacy  of  Baer's  anatomical 
theories,  337. 

Catastrophism,  discussions  regarding 
the  theory  of,  97-99,  126,  130. 

Cavendish,  Henry,  discovers  hydrogen 
gas  and  the  composition  of  water, 
31,  34,  253. 

Cell  theory,  the,  its  conception  and 
development,  330-346  ;  some  of  its 
unsolved  problems,  454-456. 

Chambers,  Robert,  his  anonymous 
argument  for  the  theory  of  trans- 
mutation of  species,  300,  301. 

Charcot,  Jean  Martin,  his  revival  of 
hypnotism,  415. 

Charpentier,  Jean  de,  first  ridicules 
and  then  becomes  an  enthusiastic 
advocate  of  the  glacial  theory, 
134. 

Chemistry,  the  contest  it  gave  rise  to 
and  its  advances  in  the  eighteenth 
century,  29-35 ;  the  phlogiston 
theory,  29-31  ;  discovery  of  hydro- 
gen gas,  31 ;  discovery  of  oxygen, 
which  led  to  the  development  of  the 
"new  chemistry,"  31-35;  solving 
the  mysteries  of  respiration,  39-41  ; 
progress  of  the  science  during  the 
nineteenth  century,  252-287 ;  dis- 
covery and  development  of  the 
atomic  theory,  252-255 ;  discovery  of 
the  laws  of  atomic  weights,  the  spe- 
cific heat  of  atoms,  and  of  isomor- 
phism, 255-262;  study  of  the  theory 
of  the  binary  composition  of  chemi- 
cal compounds  and  the  establish- 
ment of  theoretical  chemistry,  262— 
265  ;  discoveries  in  organic  chemis- 
try and  the  establishment  of  the  law 
of  molecular  structure,  265-269; 
discovery  of  the  law  of  valency, 
and  the  establishment  and  develop- 
ment of  isomerism,  269-275  ;  de- 

.  termination  of  the  character  and 
properties  of  atoms  and  molecules, 
275-278 ;  discovery  of  the  law  of 
atomic  weights  and  of  the  -'law  of 
octaves  "  lead  to  an  investigation 


of  the  probable  compound  nature 
of  the  elements,  278-287. 

Chladni,  Ernst  F.  F.,  his  theory  of 
meteorites,  159,  160,  161,  162/ 

Chloroform,  discovery  of  its  anaes- 
thetic properties,  374. 

Christol,  M.,  his  discovery  of  human 
fossils  in  the  south  of  France,  111. 

Christy,  Henry,  his  important  find  in 
the  caves  of  Dordogne,  113. 

Clark,  Alvan,  Jr.,  his  discovery  of  a 
"dark  star,"  the  companion  of 
Sirius,  75. 

Clausius,  Rudolph  Julius  Emanuel, 
aids  in  establishing  the  doctrine  of 
the  conservation  of  energy,  223- 
226  ;  investigates  the  kinetic  theory 
of  gases,  242-244 ;  points  out  the 
way  to  measure  the  size  of  mole- 
cules, 244 ;  measures  the  energy  of 
a  molecule  of  gas,  245. 

Climate,  and  the  study  of  the  influ- 
ences which  affect  it,  172-182 ; 
how  that  of  northern  India  is  af- 
fected by  the  monsoons,  191. 

Clouds,  classification  of,  and  their 
formation,  169-172. 

Comets,  theories  regarding,  and  the 
determination  of  their  character 
and  origin,  53-60;  photographed, 
79. 

Conservation  of  energy,  discovery  of 
the  law  of,  209-221." 

Contagion,  its  cause  discovered,  380- 
382.  * 

Co-ordination,  Cuvier's  law  of,  322. 

Cope,  Edward  Drinker,  his  important 
discoveries  in  the  Rocky  Mountain 
region,  and  the  story  they  tell,  114- 
121 ;  advocates  Lamarck's  theory  of 
the  origin  of  favored  species,  318, 
319. 

Corpuscles,  red  blood,  discovery  of, 
349,  350, 

Corvisart,  Jean  Nicholas  de,  intro- 
duces the  percussion  method  into 
medical  practice,  354—356. 

Couper,  A.  S.,  his  investigations  of 
the  affinities  of  different  elements, 
271. 

Croll,  James,  his  "  pre-nebular  the- 
ory," 86 ;  contends  for  many  Ice 
ages,  136;  his  estimate  of  the 


462 


INDEX 


weight  of  the  ice-sheet  over  New 
England,  150;  his  theory  of  the 
Gulf  Stream,  180,  181,  182;  his 
theory  of  solar  heat,  439. 

Crookes,  William,  his  ultra-gaseous 
theory  of  matter,  247;  advocates 
the  Proutian  theory  of  the  com- 
pound nature  of  the  so-called  ele- 
ments, 287. 

Cuvier,  Georges,  his  doctrine  of  the 
correlation  of  parts,  36;  his  study 
and  investigation  of  fossil  bones, 
which  lead  to  the  establishment  of 
vertebrate  paleontology,  91-94,  96  ; 
his  belief  in  catastrophism,  98, 
131 ;  his  disbelief  in  the  authen- 
ticity of  human  fossils,  111;  his 
investigation  of  strata  near  Paris, 
138  ;  his  theory  of  special  creation 
and  fixity  of  species,  297,  299-302  ; 
his  classification  of  the  animal 
kingdom,  321 ;  his  law  of  co-ordi- 
nation, 322;  opposes  Gall's  phre- 
nological system,  400. 

Cy  clone  >  description  of,  186. 

DAGUEURE,  Louis  JACQUES  MANDE, 
his  perfection  of  photography,  284. 

Dalton,  John,  his  solution  of  the 
problem  of  evaporation  and  pre- 
cipitation, 168,  169,  171,  172,  252, 
253  ;  his  explanation  of  the  trade- 
winds,  178,  182;  his  conception  of 
the  chemical  atom  and  his  atomic 
theory,  253-255,  259,  260,  262. 

Darwin,  Charles  Robert,  and  his 
Origin  of  Species,  105-108,  302- 
8H»;  cited  by  Lyell  to  prove  a 
change  of  level  in  continental 
areas,  126 ;  his  theory  of  latent 
heat,  171  ;  his  construction  and 
establishment  of  the  theory  of  the 
origin  of  species  by  natural  selec- 
tion, 302-317. 

Darwin,  Erasmus,  how  he  accounted 
for  the  aurora,  163;  his  prophetic 
conception  of  the  transmutation  of 
species,  290,  291,  296. 

Darwin,  Professor  G.  H.,  his  determi- 
nations as  to  the  comparative  mo- 
tion of  the  earth  and  moon,  51,  52. 

Davy,  Humphry,  his  experiments  in 
photography,  2 ;  endorses  Thomp- 


son's theory  of  heat,  27 ;  experi- 
ments on  respiration,  40 ;  his  sug- 
gestion to  account  for  the  molten 
condition  of  the  earth,  125;  dis- 
covers that  the  cause  of  chemical 
and  of  electrical  attraction  are 
identical,  206;  proves  the  trans- 
formation of  labor  into  heat,  210 ; 
melts  ice  by  friction,  225 ;  his  the- 
ory of  the  properties  of  particles  of 
matter  (or  atoms),  241,  242;  non- 
committal as  to  Dalton's  atomic 
theory,  259 ;  his  remarkable  dis- 
coveries which  led  to  the  theory  of 
the  binary  composition  of  chemical 
compounds,  262-265 ;  originates  the 
method  of  medication  by  inhala- 
tion, 366. 

Dawes,  Rev.  W.  R.,  his  discovery  of 
a  new  ring  around  Saturn,  49,  50. 

Dawson,  Sir  William,  his  study  of  the 
Laurentian  system  of  Canada,  139. 

Deluc,  Guillaume  Antoine,  his  theory 
of  evaporation,  168,  170. 

Desmoulins,  Louis  Antoine,  his  psy- 
chological researches,  400. 

Devaine,  a  French  physician,  discov- 
ers the  cause  of  the  infectious  dis- 
ease anthrax,  380,  381. 

Deville,  Sainte  Claire,  his  investiga- 
tion of  the  chemical  process  known 
as  dissociation,  273. 

Dew,  the  problem  of  its  formation 
solved,  167-172. 

Digestion,  investigation  of  its  proc- 
esses, 39,  347-352. 

Diphtheria,  the  serum  treatment  for, 
392,  393. 

Dissociation  of  molecules  and  atoms, 
investigated  by  Deville,  273 ;  an 
unsolved  problem,  447,  448. 

Donati,  Giovanni  Battista,  spectro- 
scopic  researches  of,  70. 

Donders,Frans  Cornelis,  makes  the  first 
attempt  to  time  nervous  action,  413. 

Dove,  Heinrich  Wilhelm,  his  study  of 
the  winds,  182,  183. 

Draper,  Henry,  successfully  photo- 
graphs a  nebula,  79. 

Draper,  John  William,  his  pioneer 
work  in  celestial  photography,  76 ; 
his  application  of  photography  to 
spectrum  analysis,  285. 


463 


INDEX 


Dubois,  Eugene,  his  find  of  the  ape- 
man  fossil  in  the  island  of  Java, 
120. 

Dujardin,  Felix,  his  histological  re- 
searches, 339. 

Dulong  and  Petit's  discovery  of  the 
specific  heat  of  atoms,  260,  261. 

Dumas,  Jean  Baptiste  Andre,  his 
work  in  organic  chemistry,  266, 
268,  279,  280,  346,  347. 

Dunn,  Sergeant,  his  principal  work  in 
weather  observation,  190. 

Dutrochet,  Rene  Joachim  Henri,  his 
study  of  the  processes  of  digestion, 
352. 

EARTH,  the,  Thomson's  estimate  of  its 
longevity,  74,  154;  some  unsolved 
problems  regarding,  435-442. 

Ehrenberg,  Christian  Gottfried,  dis- 
putes Mohl's  cell  theory,  343 ;  dis- 
covers the  fibrillar  character  of 
brain  tissue,  425. 

Electricity,  conception  of,  in  the 
eighteenth  century,  24 ;  how  af- 
fected by  the  discovery  of  Volta, 
28,  29  ;  its  relationship  to  galvan- 
ism demonstrated,  204,  205 ;  the 
cause  of  chemical  and  electrical 
action  demonstrated  to  be  identi- 
cal, and  the  science  of  magneto- 
electricity  established,  206-209 ; 
its  first  use  in  signalling,  207. 

Electro-chemistry,  its  accidental  dis- 
covery through  the  experiments  of 
Nicholson  and  Carlyle,  28  ;  Davy's 
theory  of,  206. 

Electro  -  magnetism,  Helmholtz  and 
Hertz's  study  and  development  of, 
227,  228. 

Encke,  Johann  Franz,  determines  the 
orbital  movement  of  comets,  57. 

Espy,  James  Pollard,  his  theory  of 
wind  storms,  190. 

Ether,  sulphuric,  discovery  of  its 
anaesthetic  properties,  369-374. 

Ether,  the,  and  ponderable  matter, 
its  displacement  of  the  "  imponder- 
ables," 228,  229  ;  its  discovery,  and 
speculations  as  to  its  constitution 
and  properties,  230-236 ;  experi- 
ments of  Helmholtz  and  Thomson 
to  prove  the  vortex  theory  of  atoms, 


236-240  ;  theories  as  to  the  distri- 
bution, mutual  relations,  properties, 
and  dimensions  of  molecules,  241- 
245  ;  also  as  to  their  outline,  ac- 
tion, temperature,  and  energy,  245- 
251  ;  the  hypothesis  that  the  vor- 
tex whirl  is  the  essence  of  matter 
itself,  251.  See  Chemistry. 

Euler,  Leonhard,his  extraordinary  con- 
clusion as  to  the  midnight  temper- 
ature at  the  equator,  175. 

Evans,  John,  aids  Prestwich  in  mak- 
ing report  on  the  paleolithic  im- 
plements found  at  Abbeville,  109. 

Evaporation  and  precipitation,  the- 
ories regarding,  and  the  determina- 
tion of  their  causes,  167-172. 

Evolution,  theories  of,  288-297,  302- 
310,  317-320  ;  some  unsolved  prob- 
lems regarding,  454-456. 

FALCONER,  HUGH,  verifies  the  paleo- 
lithic find  of  Perthes  at  Abbeville, 
109. 

Faraday,  Michael,  attributes  the  aurora 
to  magnetism,  164  ;  establishes  and 
develops  the  science  of  magneto- 
electricity,  208,  209,  226  ;  refuses 
to  accept  the  doctrine  of  the  con- 
servation of  energy,  218;  his  con- 
ception of  an  invisible,  all-pervad- 
ing plenum,  234 ;  liquefies  carbonic- 
acid  gas,  249  ;  confirms  Berzelius's 
theory  of  binary  combinations,  265. 

Favus,  its  cause  discovered,  365. 

Fechner,  Gnstav  Theodor,  his  re- 
searches in  the  new  science  of 
"  physiological  psychology,"  409- 
412. 

Fermentation  and  putrefaction,  inves- 
tigation of  the  processes  of,  375- 
380. 

Ferrel,  William,  his  rediscovery  of 
the  cause  of  atmospheric  circula- 
tion, 183,  184. 

Ferrier,  David,  his  experiments  in 
brain  localization,  420,  421. 

Fizeau,  Hippolyte  L.,  his  experiments 
on  light,  222 ;  his  experiments  on 
ether,  234. 

Flourens,  Marie  Jean  Pierre,  his  ex- 
periments in  nerve  physiology, 
417,  418. 


464 


INDEX 


Forbes,  James  David,  proves  that 
radiant  heat  and  light  conform  to 
the  same  laws,  223,  225. 

Forster,  George,  his  remarkable  cli- 
matic observations,  176. 

Forster,  Thomas,  his  theory  of  aero- 
lites, 161. 

Foucault,  Leon,  his  experiments  to 
prove  the  undulatory  nature  of 
light,  222. 

Fourcroy,  Antoine  Frat^ois,  aids  La- 
voisier in  the  development  of  a 
new  chemistry,  32. 

Frankland,  Edward,  discovers  the 
difference  in  combining  power  of 
different  atoms,  which  leads  to  the 
law  of  valency,  271. 

Franklin,  Benjamin,  tries  to  account 
for  evaporation,  168. 

Fraunhofer,  Joseph,  perfects  the  re- 
fracting telescope  and  invents  the 
heliometer,  65 ;  suggests  the  im- 
provement of  the  spectroscope,  70. 

Fresnel,  Augustin  Jean,  his  investi- 
gations of  the  phenomena  of  light, 
200-204,  225. 

Fritsch,  Gustav,  his  researches  relat- 
ing to  brain  localization,  420. 

Frommann,  Professor,  his  theory  of 
cell  formation,  454. 

Fuhlrott,  Dr.,  his  discovery  of  the 
Neanderthal  skull,  110. 

GALL,  FRANZ  JOSEPH,  originates  the 
system  of  phrenology,  399,  400,  423. 

Gafle,  Johann  Gottfried,  directed  by 
Leverrier,  discovers  Neptune,  49. 

Galvani,  Luigi,  and  the  invention  and 
application  of  the  galvanic  battery, 
27,  28. 

Galvanic  battery,  the  far-reaching 
effects  of  its  invention,  27-29. 

Galvanism,  its  discovery  and  far-reach- 
ing effects,  27-29;  its  kinship  to 
electricity  demonstrated,  204-206. 

Gauss,  Karl  Friedrick,  his  first  test 
of  the  electric  telegraph,  207. 

Gay-Lussac,  Joseph  Louis,  his  experi- 
ments with  gases,  which  lead  to  the 
discovery  of  the  molecule,  256- 
258 ;  his  discovery  of  cyanogen, 
266,  267. 

Geology,  its  ghostly  character  in  the 


eighteenth  century,  17-19;  Hutton 
labors  to  systematize  the  science, 
but  his  Theory  of  the  Earth  is  pro- 
nounced heretical,  19-23  ;  William 
Smith's  first  geological  map  of 
England,  90 ;  progress  of  the  sci- 
ence during  the  nineteenth  century, 
123-156  ;  controversy  between  the 
Neptunists  and  the  Plutonists  re- 
garding terrestrial  phenomena,  and 
the  establishment  of  the  theory  of 
the  latter,  123-125;  discussion  re- 
garding the  changes  in  land  sur- 
faces, whether  cataclysmic  or 
gradual,  125-130;  establishment 
of  the  glacial  theory,  130-136; 
study  of  the  earth's  strata,  and 
their  classification,  136-145;  con- 
sideration of  the  evidence  which 
shows  the  age  and  growth  of  moun- 
tains and  continents,  145-150  ;  evi- 
dences of  the  ^glacial  epoch,  150, 
153;  reasons  for  believing  in  the 
gradual  diminution  of  changes  in 
the  surface  of  the  earth  owing  to 
its  refrigeration,  153-156. 

Gerhardt,  Charles  Fiederic,  working  in 
the  field  of  organic  chemistry,  266- 
268  ;  revives  Avogadro's  law,  269. 

Gerlach's  histological  scheme  of  the 
brain,  428. 

Germ  theory,  Pasteur's  and  Tyndall's 
advocacy  of,  320,  386. 

Gill,  David,  photographs  a  comet,  79. 

Glacial  theory,  the  establishment  of, 
130-136  ;  the  work  of  the  ice-sheet 
in  New  England,  150. 

Goethe,  Johann  Wolfgang  von,  his 
doctrine  of  the  metamorphoses  of 
parts,  36,  102,  288-291. 

Golgi,  Camille,  this  method  of  stain- 
ing nerve  cells  and  their  processes, 
429,  430. 

Gravitation,  its  cause  an  unsolved 
problem,  443-446. 

Gray,  Asa,  an  ardent  propagandist  of 
the  Darwinian  theory,  313. 

Gulf  Stream,  the,  speculations  as  to 
its  effect  on  climate,  178-181,  182. 

HADLEY,  JOHN,  his  explanation  of  the 

trade-winds,  178. 
Haeckel.  Ernst  Heinrich.  an  enthusi- 


2G 


465 


INDEX 


astic  advocate  of  the  Darwinian 
theory,  313,  414;  favors  the  La- 
niarckian  theory  of  the  origin  of 
favored  species,  318. 

Hahnemann,  Christian  Samuel  Fried- 
rich,  his  belief  in  the  prevalence 
of  the  itch,  361. 

Hall,  Asaph,  his  discovery  of  the 
moons  of  Mars,  49. 

Hall,  Marshall,  his  services  in  the 
practice  of  medicine,  359,  360  ;  his 
important  psychological  discovery, 
403,  404. 

Haller,  Albrecht  von,  his  idea  of  the 
function  of  respiration,  39.  . 

Harding,  of  Lilienthal,  his  discovery 
of  Juno,  47. 

Hartley,  David,  his  associational  the- 
ory of  psychology,  414. 

Heat,  how  regarded  in  the  eighteenth 
century,  24  ;  Thompson's  vibratory 
theory  of,  26,  27',  the  investigation 
of,  helps  to  solve  the  problem  of 
evaporation  and  precipitation,  171 ; 
Humboldt's  study  of  its  distribu- 
tion on  the  surface  of  the  globe, 
175-177;  discovery  of  its  nature 
and  properties,  222-224 ;  the  source 
of  animal  heat  discovered,  349. 

Heidenhain,  Rudolf,  his  experi- 
ments in  hypnotism,  415,  416. 

Helmholtz,  Hermann  Ludwig  Ferdi- 
nand von,  his  theory  as  to  the  dis- 
crepancy between  the  motion  of 
the  earth  and  the  moon,  51  ;  his 
theory  of  solar  energy,  74,  437 ; 
his  share  in  the  discovery  of  the 
doctrine  of  the  conservation  of 
energy,  214,  217,  221,  225,  437; 
his  electro-magnetic  theory  of  light, 
227,  228;  his  calculations  to  prove 
the  vortex  theory  of  atoms,  238; 
opposes  the  vitalistic  conception  of 
fermentation,  379 ;  his  researches 
and  discoveries  in  psycho-physics, 
407-409. 

Hencke,  an  amateur  astronomer,  dis- 
covers a  fifth  asteroid,  47. 

Henderson,  Thomas,  Astronomer  Roy- 
al of  Scotland,  the  first  to  success- 
fully measure  a  star's  parallax,  66. 

Henle,  Friedrich  Gustav  Jakob,  his 
anatomical  researches,  332  336, 


352  ;  his  study  of  the  nervous  sys- 
tem, 404. 

Herbart,  Johann  Friedrich,  founder 
of  mathematical  psychology,  407. 

Herschel,  Caroline,  aiding  William  in 
his  investigations,  6,  7. 

Herschel,  Sir  John,  his  study  of 
double  stars,  63,  64,  65  ;  refuses  to 
accept  the  doctrine  of  the  conserva- 
tion of  energy,  218  ;  his  improve- 
ment of  the  microscope,  326,  327. 

Herschel,  Sir  William,  his  improve- 
ment of  the  telescope  and  his 
astronomical  discoveries,  5-12, 
226 ;  his  nebular  hypothesis,  13- 
16  ;  his  theory  of  the  asteroids,  47  ; 
his  study  of  double  stars  and  dis- 
covery of  their  relative  change  of 
positions,  63,  65 ;  his  unsuccessful 
efforts  to  solve  the  problem  of  star 
distance,  65 ;  his  study  of  sun- 
spots,  166. 

Hertz,  Heinrich,  confirms  Helmholtz's 
electro-magnetic  theory  of  light, 
227,  228. 

Hinrichs,  Gustav,  his  investigations 
confirm  the  "  law  of  octaves,"  280. 

Histology.  See  Anatomy  and  Physi- 
ology ;  Psychology. 

Hooke,  Robert,  his  happy  guess  as  to 
the  nature  of  light,  198. 

Hooker,  Sir  Joseph  Dalton,  his  aid 
sought  by  Darwin  in  the  publi- 
cation of  his  Origin  of  Species, 
307,  309,  310;  becomes  his  con- 
vert and  disciple,  313. 

Howard,  Edward,  his  conclusion  as  to 
aerolites,  158. 

Howard,  Luke,  his  classification  of 
clouds  and  his  theory  of  their  for- 
mation, 169,  170;  his  theory  of  dew 
formation,  170. 

Huggins,  William,  his  spectroscopic 
researches,  70,  80. 

Humboldt,  Alexander  von,  his  discov- 
eries in  terrestrial  magnetism,  167; 
his  study  of  heat  distribution  and 
its  climatic  effects,  175-177. 

Hunter,  John,  discovers  the  processes 
of  digestion,  39,  347. 

Hutton,  James,  his  geological  inves- 
tigations and  his  Theory  of  the 
Earth,  19-23,  123,  129,  153;  gen- 


466 


INDEX 


eral  acceptance  of  his  proposition 
that  "time  is  long,"  97,  102;  his 
followers  known  as  Plutonists,  123; 
and  their  final  success  in  proving 
the  igneous  origin  of  rocks,  125; 
his  theory  of  rain,  169,  172. 

Huxley,  Thomas  Henry,  the  lesson  he 
draws  from  the  evidence  of  paleon- 
tology, 117,  118;  his  estimate  of 
Darwin,  317. 

Iluygei'.s,  Christian,  originator  of  the 
undulatory  theory  of  light,  198; 
conceives  the  existence  of  the  true 
ether,  231. 

Hyatt,  A.,  advocates  the  theory  of 
Lamarck  as  to  the  origin  of  favored 
species,  318. 

Hydrogen  gas,  discovery  of,  31. 

Hydrophobia,  discovery  of  its  cure 
by  protective  vaccination,  389,  390. 

Hypnotism,  investigation  of  its  phe- 
nomena, 415-417. 

ICEBERG  THEORY,  the,  discussion  re- 
garding, 130-186;  Ihe  effects  of 
the  ice-sheet  in  New  England,  150. 

"Imponderables,"  the,  eighteenth- 
century  controversy  regarding  the 
nature  of,  24-27 ;  the  study  of,  in 
the  nineteenth  century,  192-228; 
their  abolishment,  228^  229. 

Inhalation  originated  by  Davy  as  a 
method  of  medication,  366. 

Insane,  the,  reform  in  treatment  of, 
395-401. 

Isomerism,  discovery  of,  274. 

Isomorphism,  discovery  of,  261. 

Itch  ("gale  repercutee "),  its  cause 
and  cure  discovered,  360-363. 

JACKSON,  CHARLES  T.,  his  claims  to 
the  discovery  of  the  anaesthetic 
properties  of  ether,  373. 

Jenner,  Edward,  and  his  discovery  of 
vaccination,  42,  43. 

Joule,  James  Prescott,  discovers  the 
law  of  the  mechanical  equivalent 
of  heat,  the  corner-stone  of  the  law 
of  the  conservation  of  energy,  213, 
214,  217,  218,  221,  223,  225.' 


KANT,  IMMANUEL,  conceives  the  idea  of 
the  transmutation  of  species,  291. 


Keeler,  Professor,  his  conclusions  as 
to  the  character  of  nebulas,  83. 

Kekule,  A.,  his  investigations  lead  to 
the  establishment  of  the  law  of 
valency,  271. 

Kelvin,  Lord.    See  Thomson,  William. 

Kinetic  theory  of  gases  inrestigated 
by  Ciausius  and  Maxwell,  242-245. 

Kirchhoff,  Gustav  Robert,  with  Bun- 
sen,  perfects  the  spectroscope  and 
invents  the  method  of  spectrum 
analysis,  70,  283. 

Kirkdale,  Yorkshire,  England,  dis- 
covery of  fossil  bones  in  cave  at, 
95. 

Kir  wan,  Richard,  calculates  empiri- 
cally the  temperatures  of  all  lati- 
tudes, 175. 

Kitasalo,  Dr.,  a  leader  in  the  develop- 
ment of  serum-therapy,  392. 

Koch,  Robert,  his  bacterial  investi- 
gations, 381. 

Kolliker,  Rudolf  Albert,  confirms  the 
theory  of  isolated  nerve  cells,  431. 

LAENNEC,  RENE  THEOPHILE  HYACINTHE, 
discovers  and  practises  the  auscul- 
tation method  in  diagnosing  dis- 
eases of  the  heart  and  lungs,  356, 
359. 

Lagrange,  Joseph  Lonis,  systematizes 
Newton's  hypothesis  of  universal 
gravitation,  15 ;  accounts  for  the 
accelerated  motion  of  the  moon,  50. 

Lamarck,  Jean  Baptiste,  opposes  the 
theory  of  special  creation,  103;  his 
theory  of  the  transmutation  of 
species,  293-297 ;  his  selection  of 
the  word  "biology  "  to  express  the 
science  of  living  things,  298. 

Langley,  Samuel  Pierpont,  spectro- 
scopic  researches  of,  70. 

Laplace,  Pierre  Simon  de,  solves  the 
problems  of  universal  gravitation, 
15;  completes  Herschel's  nebular 
hypothesis,  15,  16;  his  theory  of 
Saturn's  rings,  50 ;  how  he  ac- 
counted for  the  moon's  acceleration, 
50;  how  he  accounted  for  aerolites, 
158;  opposes  Fresnel's  undulatory 
theory  of  light,  203. 

Lartet,  Edouard,  his  important  find  in 
the  caves  of  Dordogne,  113. 


467 


INDEX 


Latour,  Cagniard,  discoverer  of  pep- 
sin, 347;  his  microscopical  re- 
searches, 376. 

Laurent,  Augustus,  his  work  in  or- 
ganic chemistry,  266,  268. 

Lavoisier,  Antoine  Laurent,  his  chem- 
ical experiments  and  discoveries, 
26,  31-33;  his  tragic  fate  and  the 
triumph  of  his  doctrines,  33-35 ; 
his  experiments  on  respiration,  40. 

"  Law  of  octaves,"  the,  its  discovery  1 
and  development,  280,  283. 

Leeuwenhoek,  Antonius  von,  his  mi-  j 
croscopical  researches,  329,  376. 

Leidy,  Joseph,  his  discoveries  of  the  j 
Tertiary  period  in  the  Rocky  Moun-  | 
tain  region  and  the  truth  they  teach,  I 
114-121;  his  investigation  of  the  j 
Trichina  spiralis,  363. 

Lenz,  Professor,  first  proposer  of 
gravitation  as  the  cause  of  oceanic 
circulation,  180. 

Le  Sage's  hypothesis  of  the  cause  of 
gravitation,  443-445. 

Leuckart,  Karl  Georg  Fried  rich  Ru- 
dolf, liis  investigations  of  the 
Trichina  spiralis,  363,  364. 

Leverrier,  Urbain  Jean  Joseph,  his 
calculations  lead  to  the  discovery 
of  Neptune,  48, 49  ;  his  further  cal- 
culations as  to  the  location  of  a 
hypothetical  planet  known  as  Vul- 
can, 49. 

Liebig,  Justus  von,  foremost  among 
the  workers  in  organic  chemistry, 
266,  268,  274  ;  his  important  chem- 
ical researches,  346,  347  ;  discovers 
the  source  of  animal  heat,  349  ; 
opposes  Pasteur's  doctrine  of  fer- 
mentation, 376,  379. 

Life,  some  unsolved  problems  of  cos- 
and  telluric,  449-453. 
how  regarded  in  the  eighteenth 
century,  24 ;  establishment  of  the 
undulatory  theory  of,  192-204,  223; 
HelmhoHz's  electro-magnetic  the- 
ory of,  227,  228. 

Liquefaction  of  air,  of  carbonic-acid 
gas,  hydrogen,  and  of  other  perma- 
nent gases,  249  ;  the  question  as  to 
the  liquefaction  of  air  in  our  outer 
atmosphere,  250. 

Lister,  Sir  Joseph,,  his  improvement 


of  the  compound  microscope,  327, 
328  ;  his  discovery  of  the  true  form 
of  red  blood  corpuscles,  329  ;  his 
discovery  and  development  of  anti- 
sepsis in  surgery,  382-386. 

Lockyer,  J.  Norman,  his  "meteoric 
hypothesis,"  83-86 ;  his  endorse- 
ment of  the  theory  that  our  so- 
called  elements  have  a  compound 
nature,  286,  287 ;  his  theory  of 
solar  heat,  439. 

Lodge,  J.  Oliver,  his  theory  of  two 
ethers,  235. 

Logan,  William  I.,  his  geological  in- 
vestigations in  Canada,  139. 

Long,  Crawford  W.,  his  investiga- 
tions of  the  anaesthetic  properties  of 
ether,  373,  374. 

Lotze,  Rudolf  Hermann,  his  advocacy 
of  psycho-physiology,  409. 

Louis,  Pierre  Charles  Alexandre,  his 
introduction  of  the  "  statistical 
method  "  into  the  practice  of  med- 
icine, 360. 

Lubbock,  Sir  John  William,  advocates 
the  Darwinian  theory  of  natural 
selection,  313. 

Lyell,  Charles,  the  apostle  of  uniform- 
"itarianism,  99-102,  125,  126,  130; 
convinced  by  Darwin,  endorses  the 
transmutation  theory,  107,  108, 
313  ;  his  advocacy  of  the  glacial 
theory,  131,  132;  his  citation  of  a 
fact  from  Playfair  which  is  undis- 
puted, 153;  his  aid  sought  by 
Darwin  in  the  publication  of  his 
Origin  of  Species,  307,  309. 

MAGKNDIK,  FRANCOIS,  his  services  in 
the  rational  practice  of  medicine, 
359,  360;  his  studies  of  the  ner- 
vous system,  400,  402. 

Magnetism,  its  relations  to  electricity 
discovered,  and  the  science  of  mag- 
neto-electricity founded,  207-209. 

Magneto-electricity,  Faraday  estab- 
lishes and  develops  the  science  of. 
208,  209. 

Malthus,  Thomas  Robert,  how  his 
fissay  on  Population  aided  Darwin 
in  formulating  his  theory  of  the 
origin  of  species  by  natural  selec- 
tion, 305,  306. 


468 


INDEX 


Marais,  M.,  his  description  of  a  nine- 
teenth-century miracle,  157. 

Mars,  discovery  of  its  seven  moons, 
49. 

Marsh,  Othniel  Charles,  his  discovery 
of  new  Tertiary  species  in  the 
Rocky  Mountain  region,  and  what 
they  signify,  114-121. 

Mastodon,  the  Warren,  description  of, 
119. 

Maury,  Matthew  Fontaine,  his  the- 
ory of  the  Gulf  Stream,  178-180. 

Maxwell,  James  Clerk,  determines  the 
character  of  Saturn's  rings,  50;  his 
theories  in  reference  to  electricity 
and  magnetism,  and  to  light  and 
electro-magnetism,  227;  his  testi- 
mony as  to  the  existence  of  an  all- 
pervading  plenum,  230,  234 ;  his 
investigation  of  the  kinetic  theory 
of  gases,  242-244. 

Mayer,  Julius  Robert  von,  his  share 
in  establishing  the  doctrine  of  the 
conservation  of  energy,  214,  215- 
217,  221,  225,  435,  436. 

Medical  science  :  Jenner's  eighteenth- 
century  discovery  of  the  method  of 
preventing  small-pox,  42,  43  ;  prog- 
ress of  the  science  during  the  nine- 
teenth century,  354-394;  discov- 
ery and  development  of  percussion 
and  auscultation  in  the  diagnosing 
of  disease,  354-359  ;  introduction  of 
the  "statistical  method,"  360; 
causes  of  "  gale  repercutee  "  (itch), 
of  trichinosis,  and  of  favus  dis- 
covered, 360-365;  discovery  of 
anaesthesia,  365-375;  processes  of 
fermentation  and  putrefaction  in- 
vestigated, 375  -  380  ;  cause  of 
contagion  discovered,  380-382 ; 
discovery  and  establishment  of 
antisepsis  in  surgery,  382-386; 
discovery  and  development  of  pro- 
tective vaccination  by  virus  pre- 
pared in  the  laboratory  386-390  ; 
discovery  and  development  of  the 
serum-therapy  method  of  curing 
disease,  390-394. 

Meldrum,  Mr.,  on  the  effects  of  sun- 
spots,  166. 

Mendeleeif,  Dmitri,  confirms  the  "  law 
of  octaves "  under  the  title  of 


"  periodic  law,"  280,  283  ;   his  dis- 
sociation theory  of  atoms,  448. 

"  Meteoric  hypothesis,"  the,  of  J. 
Norman  Loekyer,  83-86. 

Meteorites.     See  Aerolites. 

Meteorology,  its  eighteenth- century 
students'  views  of  the  imponder- 
ables, 25,  26 ;  its  triumphs  and 
failures  in  the  nineteenth  century, 
157-191 ;  study  and  determination 
of  the  origin  and  nature  of  aero- 
lites, 157-162;  speculations  regard- 
ing the  aurora  162-167;  problem 
of  dew  formation  solved,  and  of 
clouds,  rain,  snow,  and  hoar-frost, 
167-172;  study  of  climatic  con- 
ditions, and  speculations  as  to  the 
influences  which  affect  them,  172- 
182,  191  ;  aerial  currents  investi- 
gated, and  their  laws  determined, 
182-191;  the  greatest  triumph  of 
practical  meteorology,  191. 

Meteors,  determination  of  their  origin 
and  character,  59,  60. 

Meyer,  Lothar,  his  confirmation  of 
the  "  law  of  octaves,"  280. 

Microscope,  nineteenth  -  century  im- 
provements in,  324-328  ;  the  inven- 
tion of  the  compound  microscope, 
327,  328. 

Miller,  William  Allen,  his  spectro- 
scopic  investigations,  70. 

Mitscherlich,  Eilhard,  his  discovery  of 
isomorphism,  261. 

Mohl,  Hugo  von,  his  discovery  of 
protoplasm,  338,  339  ;  his  theory 
of  cell  formation,  343,  344. 

Mohr,  Karl  Friedrich,  his  share  in  the 
discovery  of  the  doctrine  of  the 
conservation  of  energy,  214,  215, 
221,  225. 

Molecules,  theories  as  to  their  dis- 
tribution, properties,  dimensions, 
etc.,  242-251,  275-278;  their  iso- 
morphous  property,  261 ;  establish- 
ment of  the  law  of  molecular  struct- 
ure, 265-269,  272-275  ;  some  un- 
solved problems  regarding,  448, 449. 

Moon,  the,  how  its  acceleration  is  ac- 
counted for,  50—53. 

Morton,  William,  T.  G.,  demonstrates 
the  practicability  and  benefit  of 
anaesthesia,  369,  370,  375. 


469 


INDEX 


Morveau,  Guyton  de,  and  the  new 
chemistry,  32. 

Miiller,  Johannes,  his  discovery  of 
the  resemblance  between  animal 
and  vegetable  cells,  331,  332,  337; 
his  study  of  the  nervous  system, 
404 ;  his  discovery  of  the  means  of 
hardening  and  preserving  brain 
tissues,  424. 

Murchison,  Roderick  Impey,  combats 
the  uniformitarianism  of  Lyell,  130; 
his  classification  of  transition  rocks 
into  chronological  groups,  138. 

NAPOLEON  BONAPARTE,  how  his  choice 
of  a  physician  influenced  the  prog- 
ress of  medical  science,  354,  355, 
360. 

Neanderthal  skull,  its  discovery  and 
description,  110. 

Nebulae,  investigation  of,  and  theories 
concerning,  13-17,  79-87. 

"  Nebular  hypothesis,"  the,  its  con- 
ception and  completion,  13-17,  84. 

Neptune,  how  it  was  discovered,  48, 
49. 

Neptunists,  theory  of  the,  123-125. 

Nervous  system,  the,  discoveries  re- 
lating to,  401-407. 

Neurons,  the  theory  of,  430,  431. 

New  photography,  the,  2,  5,  284-286. 

Newburg,  New  York,  description  of 
the  mastodon  found  there,  119. 

Newlands,  John  A.  R.,  discovers  the 
"  law  of  octaves,"  280. 

Newton,  Professor,  determines  the 
true  character  of  meteor  showers, 
59. 

Newton,  Sir  Isaac,  his  hypothesis  of 
universal  gravitation,  systematized 
by  Laplace  and  Lagrange,  15  ;  pro- 
nounced impious  and  heretical  in 
1700,  16;  his  blow  at  the  super- 
natural character  of  comets,  54. 

OCEAN  CURRENTS,  speculations  as  to 
their  effects  on  climate,  178-182. 

Oersted,  Hans  Christian,  his  discovery 
of  the  deflection  of  the  magnetic 
needle  by  electric  currents,  207. 

Oken,  Lorenz,  his  extension  of  the 
theory  of  metamorphoses  of  parts 
to  the  animal  kingdom,  289 ;  his 


theory  of  spontaneous  generation 
and  of  the  evolution  of  species,  298. 

Olbers,  Heinrich  Wilhelm  Matthias, 
his  discovery  of  Pallas,  44,  47  ;  his 
explosion  theory  of  the  asteroids, 
and  the  objections  to  it,  47 ;  his 
discovery  of  Vesta,  47  ;  teaches  the 
true  character  of  the  comet's  tail, 
54  ;  his  theory  of  aerolites,  158. 

Olmstt'd,  Denison,  determines  the  cos- 
mica!  origin  of  shooting- stars,  161. 

Origin  of  species  by  natural  selection, 
theory  of,  302-310. 

"  Origin  of  the  fittest,"  speculations 
regarding,  317-319. 

Owen,  Sir  Richard,  sustains  Lyell's 
hypothesis  of  special  creation,  105; 
his  discovery  of  the  Trichina  spi- 
ralis,  363. 

PALEONTOLOGY,  the  work  of  its  eigh- 
teenth-century devotees,  23 ;  the 
story  of  its  progress  during  the 
nineteenth  century,  88-122;  the 
true  character  of  fossils  first  recog- 
nized by  Da  Vinci,  88;  William 
Smith's  early  paleontological  discov- 
eries and  his  deductions  therefrom, 
89-91 ;  Cuvier's  studies  and  inves- 
tigations, which  result  in  the  estab- 
lishment of  vertebrate  paleontology, 
91-94,  96;  Buckland's  Kirkda'le 
discovery  and  the  contention  re- 
garding it,  95  ;  other  fossil  discover- 
ies, and  the  general  acceptance  of 
Button's  proposition  that  "time  is 
long,"  95-97 ;  the  theory  of  catas- 
trophism  overthrown  and  the  doc- 
trine of  unifoi  mitarianism  es- 
tablished, 97-102 ;  controversy 
regarding  the  theory  of  special 
creation,  102-105  ;  Darwin's  Origin 
of  Species,  and  the  general  accept- 
ance of  his  transmutation  theory, 
105-109  ;  fossil  discoveries  of  Fal- 
coner, Fuhlrott,  Schmerling,  and 
others,  which  demonstrate  the  ex- 
istence of  paleolithic  man,  109- 
114;  discovery  of  new  Tertiary 
species  in  the  Rocky  Mountain 
region,  and  of  vertebrate  fossils 
elsewhere,  which  prove  the  truth 
of  evolution,  114-121. 


470 


INDEX 


Pappeiiheim,  Gottfried  Heinrich,  his 
discovery  of  the  function  of  the 
pancreas,  347. 

Pasteur,  Louis,  his  services  in  the 
cause  of  organic  chemistry,  266, 
274,  375;  refutes  Pouchet's  theory 
of  spontaneous  generation,  320, 
386 ;  his  study  of  fermentation  and 
putrefaction,  375-380  ;  his  discov- 
ery and  establishment  of  protective 
vaccination,  387-390. 

Peirce,  Benjamin,  disproves  Laplace's 
theory  of  Saturn's  rings,  50. 

Penn,  Granville,  how  he  accounted 
for  the  fossil  discoveries  at  Kirk- 
dale,  95. 

Pepsin,  its  discovery,  347. 

Percussion,  its  discovery  and  develop- 
ment as  a  method  of  diagnosing 
disease,  354-356,  359. 

Perraudin,  a  chamois-hunter  of  the 
Alps,  conceives  the  glacial  theory, 
132-134. 

Perthes,  M.  Boucher  des,  his  paleo- 
lithic discoveries  at  Abbeville,  109. 

Phlogiston,  the  eighteenth-century 
theory  of,  29-32. 

Photography,  experiments  in,  by  Davy 
and  Wedgwood,  2 ;  its  services  in 
spectrum  analysis,  284—286 ;  per- 
fected by  Daguerre  and  Draper, 
284,  285. 

Phrenology,  origin  of  the  system, 
399. 

Physics,  advances  made  in  the  science 
during  the  eighteenth  century,  23- 
29  ;  controversy  over  the  nature  of 
the  "  imponderables,"  24-27  ;  dis- 
covery of  the  galvanic  battery  and 
its  far-reaching  results,  27-29; 
progress  made  in  the  science  dur- 
ing the  nineteenth  century,  192— 
229;  study  of  light  and  colors,  and 
the  establishment  of  the  undula- 
tory  theory,  192-204;  identity  of 
galvanic  and  electrical  action  de- 
monstrated, 204-206;  the  link  be- 
tween magnetism  and  electricity 
discovered,  and  the  science  of  mag- 
neto-electricity founded,  207-209; 
discovery  of  the  law  of  the  conser- 
vation of  energy,  209-221  ;  discov- 
ery of  the  nature  and  properties  of 


heat,  and  the  establishment  of  the 
science  of  thermo-dynamics,  222- 
224 ;  Helmholtz's  electro-magnetic 
theory  of  light,  227,  228 ;  displace- 
ment of  the  imponderables  in  favor 
of  an  all-pervading  ether,  228,  229; 
some  unsolved  problems,  443-449. 

Physiology,  its  eighteenth -century 
triumphs,  39-41 ;  discoveries  in 
brain  physiology,  417-423.  See 
Anatomy  and  physiology;  Medical 
science. 

Piazzi,  Giuseppe,  his  discovery  of 
Ceres,  44. 

Pickering,  Edward  Charles,  his  spec- 
troscopic  researches,  70,  73. 

Pinel,  Philippe,  his  anatomical  inves- 
tigations, 324 ;  inaugurates  in 
France  a  reform  in  the  treatment 
of  the  insane,  395-399 ;  opposes 
the  system  of  phrenology,  400. 

Pithecanthropus  erectus,  the  ape-man 
fossil  from  the  island  of  Java,  120. 

Play  fair,  John,  his  advocacy  of  the 
Huttonian  theory  of  the  earth,  123, 
126. 

Pleiades,  the,  facts  concerning,  64, 
80. 

Plutonists,  theory  of  the,  123-125. 

Poisson,  Simeon  Denis,  discovers  the 
cause  of  the  atmospheric  circula- 
tion, 184;  opposes  the  undulatory 
theory  of  light,  203. 

Pouchet,  M.  F.  A.,  his  theory  of 
"spontaneous  generation,"  320. 

Prestwich,  Joseph,  investigates  the 
Abbeville  find  and  makes  report 
thereon,  109. 

Priestley,  Joseph,  his  discovery  of 
oxygen,  31  ;  his  inexplicable  oppo- 
sition to  the  doctrines  of  Lavoisier, 
34,  35 ;  his  experiments  on  respi- 
ration, 40. 

Protoplasm,  its  discovery  by  Mohl 
and  Dnjardin,  338-340. 

Proust,  Louis  Joseph,  his  theory  of 
the  combination  of  chemical  ele- 
ments, 255,  256. 

Prout,  William,  his  theory  of  the 
compound  nature  of  the  so-called 
elements,  278-287;  his  discovery 
of  hydrochloric  acid  in  the  gastric 
juice,  347. 


471 


INDEX 


Psychology,  experimental,  its  advances 
during  the  present  century,  3 
-432  ;  the  reform  in  the  treatment 
of  the  insane,  395-401  ;  discov- 
eries regarding  the  nervous  sys- 
tem, 401-407  ;  establishment  and 
development  of  psycho-  physics, 
407—417  ;  discoveries  in  brain  phys- 
iology, 417-423  ;  establishment 
and  development  of  brain  histol- 
ogy, 423-432. 

Psycho-physics,    discoveries    relating 
to,  407-417. 

Putrefaction  and  fermentation,  their 
processes  investigated,  375-380. 

RAIN,  theories  regarding,  and  the  de- 

termination of  its  causes,  167-172. 
Ramon  y  Cajal,  S.,  his  discoveries  re- 

lating to  nerve  cells,  430,  431,  432. 
Ramsay,   Andrew  Oombie,    how    he 

accounted    for   many  of   the    lake 

basins,  153. 
Rankine,    William    John    Macquorn, 

his  researches  prove  the  law  of  the 

conservation  of  energy,   223,  224, 

225. 
Remak,  Professor,  his   microscopical 

researches  of  the  brain  and  nervous 

system,  404,  425. 
Respiration,  its  processes  investigated, 

39-41,  349,  350. 
Rontgen,  Professor,  and  the  X  ray, 

1,  2,  228. 
Rosse,  Lord,  his  studies  of  nebulae 

through  his  six-foot  reflector,  80. 
Roux,   Dr.,  his  services  in  the  cause 

of  serum-therapy,  392,  393. 
Rum  ford,  Count,  see  Thompson,  Ben- 

jamin. 
Rush,   Benjamin,   his  reform    in  the 

treatment  of  the  insane,  395,  396. 
Rutherford,   Daniel,  his  discovery  of 

nitrogen,  34. 
Rutherford,  Lewis  Morris,  his  spec- 

troscopic  researches,  70,  72. 


SAINT-HlLAIRE,     GEOFFROY,    his 

cacy  of  the  transmutation  theory, 
104;  opposes  Cuvier's  special-cre- 
ation hypothesis,  and  partially  en- 
dorses the  Lamarckian  theory,  300, 
318. 


Saturn,  discoveries  relating  to,  49,  69. 

Savary,  M.,  accounts  for  the  elliptical 
orbits  of  double  stars  by  the  laws 
of  gravitation,  64. 

Scheele,  Karl  Wilhelrn,  his  discovery 
of  oxygen,  31  ;  his  physiological  ex- 
periments, 40. 

Schiaparelli,  Giovanni  Virginio,  his 
establishment  of  the  cometary 
origin  of  meteors,  59. 

Schleiden,  Matthias  Jakob,  his  dis- 
covery of  the  function  of  the  cell 
nucleus,  331,  332,  345;  his  discov- 
erv  of  so-called  free-cell  formation, 
343. 

Schmerling,  Anton  von,  his  impor- 
tant discoveries  at  Engis,  Westpha- 
lia, 111. 

Schoenlein,  J.  L.,  discovers  the  cause 
of  favus,  365. 

Schultze,  Max  Johann  Sigismund,  dis- 
covers the  identical  character  of 
vegetable  and  animal  cells,  340. 

Schwann,  Theodor,  his  cell  theory, 
331-336,  337,  338,  343,  345;  his 
discovery  of  pepsin,  347 ;  his  mi- 
croscopical researches,  376,  404. 

Scientific  problems,  some  unsolved, 
433-457 ;  regarding  the  sun  and 
earth,  435-442;  in  physics,  443- 
449;  of  life  and  the  evolution  of 
living  matter,  444-456  ;  of  anthro- 
pology, 456,  457. 

Scrope,  G.  Poulett,  his  work  account- 
ing for  the  origin  of  volcanoes,  124. 

Secehi,  Father  Angelo,  his  researches 
in  spectrum  analysis,  70,  72. 

Sedgwick,  Adam,  his  classification  of 
transition  rocks  into  chronological 
groups,  138. 

Serum-therapy,  discovery  and  devel- 
opment of  the  system  of,  390- 
394. 

Shooting-stai'S,  determination  of  their 
origin,  59,  60. 

Simpson,  Sir  J.  Y.,  his  discovery  of 
chloroform  as  an  anaesthetic,  374. 

Sirius  and  its  "  invisible  "  companion, 
74,  75. 

Six,  Mr.,  his  theory  of  dew  formation, 
171. 

Small-pox,  Jenner's  discovery  of  the 
means  of  its  prevention,  42,  43. 


473 


INDEX 


Smith,  William,  "  the  father  of  Eng- 
lish geology,"  his  paleontological 
discoveries  and  his  deductions 
therefrom,  89-91  ;  his  study  of 
strata  as  a  key  to  the  earth's  chro- 
nology, 137,  138. 

South,  James,  aids  John  Herschel  in 
his  investigation  of  double  stars,  64. 

Spallanzani,  Abbe,  discovers  the  proc- 
esses of  digestion,  39,  347 ;  his  ex- 
periments on  respiration,  40. 

Special  creation,  discussions  relating 
to  the  hypothesis  of,  91-97,  104, 
105,  297-302. 

Spectroscope,  its  perfection  by  Kirch- 
hoff  and  Bunsen,  and  its  solar  and 
sidereal  analyses,  70-76,  283,  284 ; 
its  necromantic  power,  76 ;  its 
application  to  nebulae,  80. 

Spectrum  analysis,  its  remarkable  dis- 
closures, 70-76,  283-287. 

Spencer,  Herbert,  advocates  the  Dar- 
winian theory,  313,  316  ;  favors  the 
Lamarckian  conception  of  the  ori- 
gin of  favored  species,  318;  his 
theoretical  study  of  psychology,  415. 

Spontaneous  generation,  Pouchet's 
hypothesis  of,  320. 

Spurzheim,  Kaspar,  advocates  phre- 
nology, 400. 

Stars,  double  or  multiple  stars,  and 
star  clusters,  the  investigations  of 
the  nineteenth  century  relating  to, 
60-76. 

"Statistical  method,"  the,  its  intro- 
duction into  medical  practice,  360. 

Stethoscope,its  invention  and  improve- 
ment, 356,  359. 

Storm-centre,  description  of,  186, 189. 

Struve,  F.  G.  W.,  his  discovery  of 
double  stars,  64  ;  solves  the  prob- 
lem of  star  distance,  66. 

Sun,  the,  its  elements  discovered  by 
spectrum  analysis,  70-72 ;  Helm- 
holtz's  theory  of  solar  energy,  74 ; 
some  unsolved  problems  regarding, 
435_442 ;  estimate  as  to  its  heat- 
giving  life,  438. 

Sun-spots,  effects  of,  166. 

TAIT,  PETER  GUTHRIE,  his  measure- 
ment of  the  free  path  of  molecules, 
247. 


Talbot,  William  Henry  Fox,  his  ser- 
vices in  the  perfection  of  photog- 
raphy, 285. 

Temperature,  the.  absolute  zero  of, 
250. 

Tetanus,  the  serum  treatment  for,  392. 
Theory  of  the  Earth,  James  Hut- 
ton's,  20-23. 

Thermo-dynamics,  and  how  the  sci- 
ence originated,  223,  224. 

Thompson,  Benjamin  (Count  Rum- 
ford),  his  vibratory  theory  of  heat, 
26,  27  ;  he  proves  the  transforma- 
tion of  labor  into  heat,  210. 

Thomson,  Thomas,  advocates  Dalton's 
atomic  theory,  259. 

Thomson,  William  (Lord  Kelvin),  his 
estimate  of  the  earth's  longevity, 
74,  154,  441  ;  aids  Joule  in  estab- 
lishing the  doctrine  of  the  conser- 
vation of  energy,  218-223,  225; 
his  doctrine  of  the  dissipation  of 
energy,  223,  224 ;  his  studies  in 
thermo-dynamics,  223,  224,  227; 
his  calculation  of  the  probable  den- 
sity and  rigidity  of  ether,  235  ;  his 
conception  of  the  vortex  theory  of 
atoms,  and  his  verifying  experi- 
ments, 238-240;  calculates  the 
dimensions  of  a  molecule,  244, 
245  ;  refuses  to  recognize  any  re- 
pulsive power  in  molecules,  246 ; 
his  estimate  of  the  heat-giving  life 
of  the  sun,  438, 

Titanotheres,  or  Brontotheridce,  evolu- 
tion of,  121. 

Tournal,  M.,  his  discovery  of  human 
fossils  in  the  south  of  France,  111. 

Toxine  and  antitoxine,  their  discovery 
and  introduction,  390-394. 

Trade-winds,  study  of  their  origin 
and  effects,  177,  178,  182. 

Transmutation  of  species,  doctrine  of, 
105-108,  293-297,  302-310,  317- 
320. 

Treviranus,  Gottfried  Reinhold,  his 
theory  of  the  transmutation  of 
species  published  the  same  year  in 
which  Lamarck's  first  appeared, 
398;  foreshadows  the  cell  theory, 


Trichina  spiralis,  its  discovery,  363- 
365. 


473 


INDEX 


Trichinosis,  character  of  the  disease 
and  its  cause  discovered,  363-365. 

Take,  William,  inaugurates  reform  in 
treatment  of  the  insane,  395. 

Tyndall,  John,  his  advocacy  of  May- 
er's doctrine  of  the  conservation  of 
energy,  221,  223;  and  of  Darwin's 
theory  of  natural  selection,  313; 
his  endorsement  of  the  germ  the- 
ory, 320,  386. 

ULTRA-GASEOUS  or  fourth  state  of 
matter,  theory  of,  247. 

Undulatory  theory  of  light,  establish- 
ment of,  192-204. 

Uniformitarianism,  Sir  Charles  Ly- 
ell's  advocacy  of  the  doctrine  of, 
99-102,  127/131. 

VACCINATION,  its  discovery  as  a  means 
of  preventing  small-pox,  42 ;  its 
application  as  a  preventative  of 
other  diseases  by  virus  prepared  in 
the  laboratory,  386-390. 

Valency,  development  of  the  law  of, 
269/275. 

Valentin,  Gabriel  Gustav,  his  study 
of  pancreas,  347. 

Van  't  Hoof,  Professor,  his  establish- 
ment of  stereo-chemistry,  448, 146. 

Venetz,  M.,  an  early  believer  in  and 
advocate  of  the  glacial  theory,  134. 

Vertebrate  paleontology,  establish- 
ment of,  91-97. 

Vinci,  Leonardo  da,  his  early  recog- 
nition of  the  true  character  of  fos- 
sils, 88. 

Virchow,  Rudolf,  his  demonstration 
of  Schwann's  cell  theory,  344,  345  ; 
his  researches  which  lead  to  the 
discovery  of  trichinosis,  363,  364. 

Volta,  Count  Alessandro,  his  inven- 
tion of  the  voltaic  pile,  27,  28. 

Vortex  theory  of  atoms,  the,  experi- 
ments to  prove,  236-240  ;  an  un- 
solved problem,  446,  447. 

Vulcan,  a  hypothetical  planet  located 
by  Leverrier,  49. 

WALLACE,  ALFRED  RUSSELL,  his  re- 
markable conception  of  the  theory 
of  natural  selection  contemporane- 
ously with  Darwin,  307-310. 


Waller,  Professor,  his  discovery  of 
"  trophic  centres,"  427. 

Warren,  John  C.,  mounted,  described, 
and  gave  name  to  the  mastodon 
found  at  Newburg,  N.  Y.,  119. 

Water,  its  composition  discovered,  31, 
34,  253. 

Weather  bureaus,  their  principal  oc- 
cupation, 186,  191. 

Weber,  Ernst  Heinrich,  his  experi- 
ments and  discovery  in  psycho- 
physics,  409-412. 

Weber,  Wilhelm  Eduard,  makes  a 
practical  test  of  the  electric  tele- 
graph, 207 ;  his  study  of  the  ner- 
vous system,  405. 

Wedgwood,  Josiah,  invents  the  py- 
rometer, 24. 

Wedgwood,  Thomas,  his  experiments 
in  photography,  2,  5. 

Weismann,  August,  opposes  La- 
marck's theory  of  acquired  vari- 
ations in  the  origin  of  favored 
species,  318;  elaborates  a  hypo- 
thetical scheme  of  the  relations  of 
intracellular  units,  455. 

Wells,  C.  W.,  his  solution  of  the 
problem  of  dew  formation  and  of 
the  precipitation  of  watery  vapor 
in  any  form,  170-172. 

Wells,  Horace,  the  first  to  administer 
an  anaesthetic  in  a  surgical  opera- 
ation,  369. 

Wenier,  Abraham  Gottlob,  the  pro- 
pounder  of  the  Neptunian  theory, 
his  belief  in  the  aqueous  origin 
of  the  solids  of  the  earth's  crust, 
123;  his  belief  in  the  uniformity  of 
strata  over  the  whole  earth,  136, 137. 

Wilson,  Patrick,  his  theory  of  dew 
formation,  171. 

Winds.     See  Aerial  currents. 

Wohler,  Friedrich,  his  synthesization 
of  urea,  265,  266 ;  his  investigation 
substantiates  the  binary  theory  of 
Berzelius,  268 ;  his  discovery  of 
isomerism,  274; -his  important  ser- 
vices to  physiology,  346,  347 

Wolff,  Kaspar  Friedrich,  founder  of 
the  science  of  embryology,  36 ; 
foreshadows  the  cell  theory,  336. 

Wollaston,  William  Hyde,  discovers 
the  identity  of  galvanism  and  elec- 


474 


INDEX 


tricity,  205 ;  his  observation  of 
chemical  combinations  confirms 
Dalton's  atomic  theory,  256,  259  ; 
his  improvement  of  lenses,  325, 
326,  327. 

Wortman,  J.  L.,  his  fossil  lineage  of 
the  edentates,  121. 

Wundt,  Wilhelm  Max,  his  psycholog- 
ical discoveries,  414,  415. 

"  X  RAY,"  its  discovery,  1,  2,  228. 

YOUNG,  CHARLES  AUGUSTUS,  his  spec- 
troscopic  researches,  70. 


Young,  Thomas,  his  establishment  of 
the  undulatory  theory  of  light,  27, 
192-204,  225;  confirms  the  identity 
of  galvanism  and  electricity,  205; 
practising  medicine  and  studying 
Egyptian  hieroglyphics,  206;  the 
real  discoverer  of  the  ether  231, 
232. 

ZOLLNRR,     JOHANN     KARL     FRIEDRICH, 

his  cometary  theory,  54,  55;  his  in- 
terpretation of  the  diversities  in  the 
spectra  of  stars,  73. 


THE   END 


14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

LOAN  DEPT. 

This  book  is  due  on  the  last  date  stamped  below,  or 

on  the  date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


General  Library 

niversity  of  California 

Berkeley 


LD  21-100m-2,'55 
(B139s22)476 


r, 


,     •:     , 


VC  22755 


L-       *."     ~        ^ 


